Regarding hedges: I can experiment with it, but there's a couple things preventing me from thinking it's a good idea:
- Practical issue: Generality; people will want to start using these literally everywhere, which I'm afraid would be a pretty noticable difference in itself.
- Technical issue: Leaf blocks in MC are, generally speaking, an absolute pain in the ass to work with due to the ways biome shading works. I'd have to actually attempt it to see if it's the case for slabs/stairs/hoppers though.
Regarding flowers: We made the decision a long time ago, back when I was working on the nature update, to separate adding new crop blocks to adding new flower blocks. The reason for this is that adding new crop blocks will require an organized team to update older fields, replacing the makeshift crop representations (most of them are thankfully indexed at /warp jobs) with the new blocks. If people think more crops/herbs/flowers need to be added, these things would need to be sorted out first but it could be done.
That said, a lot of suggestions have been compiled already and the upcoming update is mostly intended for Highgarden + Oldtown + other small additions and changes.