Interesting thing about eliminating Yar: the bizarre thing I found last time I watched thru season one of TNG that I hadn't ever noticed before is how completely inessential she was. I think it must be because she was conceived as something special, but when Justman and Berman started pushing Gene to include a Klingon marine character, Yar's usefulness to scripts effectively ceased, because everything you might reasonably expect Yar to do could be done better by Worf. This is never more overtly pronounced than in Hide & Q, where Q eliminates Yar from the game without her even being able to get off a shot at him, and for the rest of the episode the role she might reasonably have been expected to play down on the planet is instead taken... by Worf. Tasha Yar was basically made irrelevant from the start. Without Worf there, she would've been functional... but the series just wasn't big enough to sustain the both of them together.