My guess is always that if a designer comes along and suggests a new interface or creates design components that can be used that maybe need some engineering re

My guess is always that if a designer comes along and suggests a new interface or creates design components that can be used that maybe need some engineering resources the priority will always be on "let's make it work first and support all these edge cases we programmers like to think about". With most projects already stretched pretty thinly on engineering resources that's the natural outcome even if it would be better to have less features, but easier to use for a beginner or regular person before building out the whole thing.