> (4) linear / uniqueness types (not exactly the same, but both can be used to ensure safe memory management) impose significant mental overhead on programmers as they prohibit many common patterns

Such as?

I've found that linear style is generally just good coding style. When I get caught up on something I can't express linearly, it generally means I was trying to plough through with a dodgy approach; stopping and thinking through would have resulted in better code even in a GCed language.