I love Rust, but I do have my own list of grievances… trying to hold off spamming them here though! 😅 Many of them I can forgive, given the constraints Rust has faced over its development, but they give me enough itches to contemplate playing with my own ideas!
It's pretty rough, pretty personal, sometimes pretty superficial/subjective, and I'm sure I've left some stuff out, but these are the things that have frustrated me with Rust over the years:
Of these I’m optimistic that the trait objects situation will be fixed eventually. It’s sitting in a place where improvements in all the areas you mention should be backwards compatible.