Well, there was a strain of fan mentality that cried out for "a fitting death" for Yar. What happened to her in "Skin Of Evil" would have been commonplace for more realistic dramas of the day - the way supporting characters might die on a drama like "NYPD Blue" for example - and that was probably GR's intent in this case. Trek is, fortunately or unfortunately, a kind of "moral comfort food" for lots of folks.
I thought Tasha's death in "Skin of Evil" was appropriate for her occupation and character. She died doing her duty, going first into a dangerous situation ahead of her commanding officer. Moreover, I found it far more dramatic than the assumed hero's sacrifice of "Yesterday's Enterprise" because it was so quick and unexpected.
And as much as I love "Yesterday's Enterprise", I loath what came as a result of it--Sela and her whole soap operish with a pseudo-science-fiction twist development.