I don't think they've really tried in a long time when it comes to comedy. Probably because they had Kochikame, Gintama, Saiki & Isobee that were all so solid for so long, but all ended within such a short period of each other.
David was always more of a romcom than anything, so I think it fits into that niche better, even if it was marketed as a gag. And Japan was trying something very specific that was a significant gamble, so it's really not a surprise it got nowhere. Either way, that's only two series. They really have to start like 3x that to hope to get one that resonates with people. That's how Jump has always been with all genres.
As far as recent comedies go, we had Conquer You (2018 25), Lycopene (2017 45), Hungry Marie (2017 13), Spring Weapon (2016 46), Samon (2015 43) & I'm unsure on what Devilyman was? (2015 26). Maybe a few others that are arguable what genre they actually are, but it's still only like 2 a year from the last 4 years, and they only really started losing competition from late 2017 onwards. The current situation is just part of the cycle honestly, and this is the beginning of a new era for the genre in the magazine. Comedy is a staple, and as such, there will always be something that resonates with people, they just have to find what. Most of us here do want a good new comedy for the magazine, and I'm sure that's true for the majority of their audience as well.