I would honestly like to see this actually, but to a certain extent. What staiain was playing is overkill imo, but if a pro player would like to map something like that, be my guest. Obviously osu!mania should not auto-generate something like that. I'm assuming making an algorithm for this tho is not that easy to do, but if you could add note density to strong beats, for example, it would make the maps more interesting. Adding note density randomly is just bad. osu!mania actually kinda does that already sometimes, which is annoying.
I'm not the best 4k player, but I've had quite some experience with it.
@MMzz: osu!mania is a really different type of game than our other modes. I still agree there should be sense in what we do in this new mode, but to an extent, we should be allowed to break "certain barriers of sense" that we could not in other modes. As I said, something like what staiain did is just overkill, but that isn't what this request is asking for.