It's hard to tell. I personally thought Yar as a character was rather two dimensional so I really didn't much mind her departure. Certainly her alternate timeline returns and evil Romulan kids weren't any better, even when the writing had improved.
It could be she would've been developed more as the writing and characterization became better. It also could be her fears of spending seven years saying "opening hailing frequencies" were founded.
Crosby opting out of her contract didn't seem to be a good career move though. Did she ever get a long term project again after that? That was something I should imagine would be stapled to every job application she filled out.