I've said it before in another thread, but I'm actually glad it worked out so that Tara didn't come back. Not because I have anything against the character, but Buffy's storyline in S6 was all about her chronic depression in coping with being dragged back to life against her will by people she trusted. Since there is no indication that Tara would go anywhere other than a heavenly dimension (she died a natural death, she was, let's face it, one of the nicest people on either series). The idea of Buffy herself doing the same thing back to one of her friends a year or so down the line just doesn't sit right with me. I mean, I know the writing in S7 was pretty inconsistent, so maybe it would have fitted in anyway in that sense 😛 But given that Joss and the writers went with that story for Buffy in S6, they should have at least kept consistency with it.
Tara's death was horrible for Willow, and heartbreaking. But Tara (if we go by what happened to Buffy) was at rest now, and by the last half of series 7, whilst Willow misses Tara, and loved Tara, she is learning how to live without her and moving on with her life.
Saying that, whilst I liked Tara well enough, she was never one of my favourite characters, I would likely feel different if it were one of my favourite characters and there was a chance that they could have returned.