Ko, unlike hatsus with their conditions and pledges, is just an ordinary move, so the risk of focusing all your Nen into attack doesn't add an "X factor" to it. Feitan did get punished by it, but only through a crappy emission attack. Zazan isn't even Emission so it was just a run of the mill aura blast. Still strong enough to cause serious damage to Feitan though. Obviously if Zazan had punched Feitan instead he would've been instantly vaporized. Of course, his failure to end the fight with a direct hit Ko is slightly less explainable.
I think the point is that Pariston was making life difficult for Netero, and he probably has political power up top as well (Netero's boss is probably someone within the political sphere), not to mention the fact that Netero's "boss" wasn't even shy from using nukes. It was Netero who thought about the collateral damage and went in with a few hunters. But as a failsafe, he had a miniature nuke within him. I also get the feeling that Netero wanted to fight the King one on one. So it didn't matter, so long as the rest of the extermination team took out the small fry and kept the Royal Guards busy.
How is it not useful? Bungee Gum you can tie people's arms or legs together, reflect projectiles, shoot projectiles, lengthen attacks, use it as apparatus for extra mobility and mostly importantly, it can act as a cushion against physical attacks. It's not bad, we just haven't seen it applied all that much. Furthermore, Hisoka is extremely proficient in hand to hand combat. Morel's abilities are nice, but how good is he in a melee?
You're too fixiated on that there has to be something called a 'hatsu' versus a 'basic move'. Zeno said Netero is powerful because you can't predict how he allocates his aura at all. This is one of the basic training moves and yet that is also what makes Netero strong, because he can do one of the most basic things better than anyone else can. If someone created a move call "Uber Punch" where it's just a single punch and if you get hit anywhere else you die and if you get hit for a short period after you use it you also die, does that sound risky? It sure is a lot riskier than anything we know of besides perhaps Uber Gon's transformation (his price is paid regardless of the outcome, while "Uber Punch" you can certainly avoid paying the price if you kill the opponent in one hit), so by definition "Uber Punch" has to do incredible damage. And yet "Uber Punch" is exactly the same as Ko. If Ko does not have the same payoff as this hypothetical 'Uber Punch' Hatsu, nobody would ever use Ko unless they're insane.
Ko is pretty much the beginning and the end. It's the first 'Hatsu' like the move you'll learn and it's likely the last 'Hatsu' like move you'll learn in terms of power. The risk of Ko generally greatly outweighs the reward, which is why people develop other moves that doesn't involve getting themselves killed 99% of the time. When Gon attempted to use Ko to block Razor's ball and got knocked to the wall, what should've happened is his internal organs should've spilled from the impact and his lower body should've been separated from the rest of his body from the force, because by definition the rest of his body is in the state of Zetsu and cannot possibly withstand the collatoral impact. Of course Gon being Gon he just gets up and continue fighting because he can't possibly die. Zetsu versus anything is not 'seriously wounded'. It's anything that hits someone in Zetsu state leads to instant death. We've been repeatedly told fighting someone without aura is basically the same as having a death wish, but apparently this never applies to Ko.
For Netero, there's no way he or the Hunter's Association is the one in possession of the Rose let alone have the power to decide that it is okay to use a weapon that can potentially wipe out an entire country (the entire population were gathered in the blast radius). There's obviously some kind of powerful UN-like organzation that supplied the Rose to Netero and told him he's authorized to use it if he has to. This entity has power that far exceeds that of Hunter's Association politically let alone Pariston. So if there are really more powerful members Netero could've gotten then whoever authorized the Rose attack could've easily pulled strings since whoever supplied the Rose still wants to avoid using it if at all possible. We see that if the news of the Rose usage gets out to the public the Hunter's Association has to take the blame. What does that mean? They'd be lucky if blame just be the entire organization gets disbanded for what commiting an act of genocide. The entire Hunter's Association could've been sacrificed by whoever Netero's backers are as there was never any guaranteed the public wouldn't find out about the Rose usage, or that the Rose wouldn't detonate while inside the palace and thus killing an entire country's population. And yet these powerful backers were unable to overcome Pariston? Netero obviously had people he thought was the best he can get. Morel and Novu talking about Pariston getting in the way is supposed to just highlight the fact that Hunter's Association has its own problems, but the team they assembled is still meant to be the best they could get.
Ging is one of the few guys who clearly knew the entire plan all along. So you're saying one of the most powerful guys in the world, who also respected Netero a lot, was content with letting Netero blow himself up while the fate of the entire human race is on the line, just so that he wouldn't have run into Gon? No the point is that even someone as powerful as Ging was unlikely to make a difference in the fight so Netero didn't gather more people. If he could, then the entire Hunter's Association is simply beyond salvaging. Honestly the whole concept of Zodiac is a joke. They are supposed to be the ones who respected Netero the most, and apparently most of them knew Netero was going to blow himself up. So Pariston was giving them problem internally, but they can get around that if they simply quit the organization. Pariston certainly has no jurisdiction over people outside the Association, so apparently Netero's life was not worth quitting the prestiegious position of the Zodiac. They all talk about how Netero is a legend and someone they rever the most but if you got to quit your cushy job as Zodiac, that's obviously asking way too much.
For Hisoka, people need to stop drinking the 'rubber is awesome' coolaid championed by HXH and OP. If you're in a world where you're constantly having to fight for your survival, rubber isn't going to be your first choice of power. You'd be crazy if you pick it over lightning, even though rubber/bubblegum apparently beats lightning in both worlds. Hisoka fights well despite of his ability, not because of his ability. In his age group he is the most physically powerful non-Reinforcement user by far, and we see that all his moves with the bungee gum relies upon his superior physical strength. It's because his hands have incredible strength that he is able to pull his enemies or withstand the impact from reflecting their attacks. Against someone like Razor, who is far more powerful physcially than Hisoka, we see that theory falls apart. Hisoka has to cancel his ability even against one of Razor's clones, because it's implied that even the clones are stronger than him physically, so they can easily yank him instead of the other way around. He broke all his fingers trying to reflect Razor's attacks, which shows that he has to take a signifcant portion of the enemy's attack when reflecting them. It works fine against someone physically weaker than you, but it sure won't work against someone like Razor. And why wouldn't Morel be good at hand-to-hand? As Pariston puts it, one of the key attributes for Hunters is strength since they do a lot of fighting. How can anyone who managed to move up in the Hunter's Association somehow not be good at fighting unless their role is purely bureaucractic? Even someone like Biscuit who sure doesn't look like she'd be good at hand-to-hand is obviously extremely good at combat, so why would someone Netero rely on somehow be bad at hand-to-hand?
Throughout HXH there is this concept of abilities more suited for combat or not. For example Big Bang punch is obviously very suited for combat. So is Pain Packer. This makes sense since Spiders pretty much spend all their time killing people or avoid getting killed. On the other hand, someone like Biscuit has an ability that's clearly not suited for fighting. Hisoka's ability falls into the latter category, and he makes that up by being extra strong physically for his age group. That's fine when he's fighting guys within his age group where he can be confident that he's the strongest unless it's a Reinforcement user, and against Reinforcement users you can argue his superior tactics/intelligence, combined with the fact that Reinforcement users aren't likely to have interesting moves, is enough to get him through, though I'd argue he has a surprisingly hard time in his fight against Reinforcement users so far.
