You could apply this logic to more advanced mapping, if you really wanted to. One doesn't suddenly get brand new-feeling maps each time just because you're using ZDoom features. The creativity involved with shaping new and interesting places is what keeps stuff feeling fresh, which is possible to accomplish in all formats. I could boil down your logic even further and say that mappers have all been making the same map for twenty-seven years, only altering the layout and monster placement to make it feel new. That sounds ridiculous, doesn't it?
The idea of "there's less fancy features to work with in these formats, which inherently equals less creativity and less reason to use it" is a baffling one, and it feels like you don't care about how features are used and instead just want them to exist for the sake of "more features". That's a sort of thinking that I can't stand, especially as someone whose mapping ethos tends to steer towards "less is more". My mapping is pretty straightforward, and that's the way I like it to be. Everything I want to work with is doable in, say, Boom (or MBF21 I suppose, now that this exists and supports a type of MAPINFO), and as a result I have no reason to use something like UDMF. Being limited to a source port I cannot stand using (GZ) for loads of features I can guarantee you I won't use simply doesn't sound worth it to me.