It fit the tone of the story IMO. A tale that dark, centered around a corporation that ruthless, couldn't possibly have ended without all of the main characters dead. What makes A3 satisfying for me is that unlike the other victims, Ripley -- who would've died like them -- ended up dying on her own terms, simultaneously taking out the last of the alien species and denying the Company what they've been after for the last century. She took a gruesome, unavoidable fate that we've been familiar with since the first film and used it to give Weyland-Yutani and the entire xenomorph species the finger.
...which is why I'm not that big on Resurrection. Don't have a problem accepting A3 as canon, but A4? It's not only unnecessary after the absolute closure we got in the previous film, but it also takes a dump all over Ripley's actions by bringing her (and the creatures) back.
I'm game to bring Hicks back, though. Not sure what I'll consider canon and what I won't, but I'm happy as long as we get another good Alien film. Been a while.