Well said, JustKate
I think all of the cast seemed a bit flat in seasons one and two, personally, and maybe a part of their perceived improvement was, as you suggest experience. I'd like to think that Crosby would have gotten better. (I think she did okay in "Pet Semetary" - but like you say, "just okay.")
And, also, there are definitely worse ways to go. I don't think her death was "meaningless." "Senseless"? Perhaps. "Random"? Definitely. But "Yesterday's Enterprise" mischaracterized it, IMO. I think they could have done a job presenting a better reason for Yar to sacrifice herself there without demeaning her original death.