The stupid thing about this powerups concerning the Sharingan, all this "ultimate ocular jutsus", even if they have a cost, during a battle it has litle play, remember how sasuke charge in against Raikage, then Mizukage, then danzou, and then kakashi, always using his Susano'o? We were told that using susano'o causes a massive pain in the user's body, but then again, they keep using it as base defence in most cases (see last fights of sasuke, madara and even itachi now)... So they were intoduced and having a significant disadvantage, but we don't see that during a fight. About Izanagi, we were told that it costs the user his eye, yet Danzou's Izanagi was imperfect, he couldn't wild it well, on the other hand, Tobi did used his, now, the thing i'm not so shure, is if Tobi can use Izanagi withou using his eye, or becouse he can use it for longer periods of time... But that has also little relevance, if you consider that he has hundreds of sharingans pilled waiting to be used... So you see, all the downsides of the jutsu have no interference during a fight.
But the most troublesome thing is that all thise magnificent Ocular Jutsus bellong all to the same eye, and if you consider all the three eyes, you have Byakugan as the one clearly the poor side of the bunch... Rinegan allows you to deflect all incoming attacks, allows you to suck chakra instantly, to revive people from the dead, to read everything he experienced, to transform any part of your body into a deadly weapon, to share vision, change your sumunings, everything; Sharingan allows you to quiqly put a genjutsu into somebody, read every movement your enemy makes, allowing you to copy any technique, grants you near impervious defence, deadly fire attack, near unbeatable illusions (tsukyomy, Izanagi) and now it appears it even enables you to see the future, ar create a future for you (waiting for the chapter), and what can Byakugan do for you? It enables you to see the chakra flow (they all do that

) a litle better that the other eye jutsus, grants you wide field of vision, but with all this new techniques related to the others eyes Byakugan is without a doubt the number 3... It doesn't even grant you a decent technique...