I hope it's not a hot take to say that if a designer can't make their UI pretty without sacrificing usability, then they failed as a designer. The whole point of this job isn't just to make things look pretty, but to also consolidate it with specific constraints. In UI design, such a constraint is usability. Shitting all over that is easy and it shows that you suck at your job.
I think designers would do a better job of not crippling UIs in the name of aesthetics if everything on their computer was using the very UIs they created. Make them use them every day, for everything. See if they still like it so much.