Yeah, I agree with you. And I really do think that they conceived this mainly as a tragic hero story, bringing down her sworn enemy but paying with her life. And then they fucked it up at the end, because they wanted her death to have 'maximum impact' for the ongoing story, making it about Reese before that tragic hero story was concluded on her own terms. But for me, this last episode does not invalidate the fact that she was indeed a great character for two and a half seasons.

... thinking about it, unlike all our other 'dead but not' characters she probably had to die (first) because she was the good guy, unlike them, she didn't 'need' the second chance. The tragic hero in a show with essentially post-tragedy characters. Except that now she is missing as exactly the unique moral point in this universe.