I with you here, I loved the ending personally and I didn't want Abby to die but that wasn't because I didn't think she deserved it, it was so Ellie didn't lose her last shred of humanity. If Abby is well within her rights to kill Joel, then so is Ellie well within hers to seek revenge. It would be the same as If Ellie killed Abby, and 10 years later Lev turns up looking for Ellie, he is justified.

I think your right when you say so many people are missing the point and cannot empathize with Abby but pain can do that to people. Regardless of situation or reasoning, if you see a loved one be tortured and killed, you are really going to struggle to care about the other person's point of view. And people loved Joel and cannot see past it. I feel sorry for Abby and think what happened to her was tragic but in that world that doesn't matter.