I don't think she was miscast. Sure, her voice was softer than you'd expect for a "tough girl" character, but I found that a positive thing, because it kept her from being a stereotype.
I'm with you.
I agree with this. I liked Yar in S1. She had frustratingly little to do, but she's competent and Crosby managed to play that without reducing her to a stereotype.
Yes, she does suffer from bad writing at times which makes the character seem ludicrously weak, but I don't think that can be blamed on the casting or on the fact that she's a tiny blonde woman. TNG is notorious for robbing its characters of their professional competence in order to facilitate plot, especially in S1. Hell, by Best of Both Worlds, Worf is still able to fire at an unobstructed target five feet away and miss. Greedo couldn't have missed that shot.