Jennifer Aniston is a good actress in my opinion. She and Matthew Perry (and Lisa Kudrow) always delivered during the more serious moments of Friends, particularly when Rachel confided in Chandler about the separation of her parents at her birthday party. That, for me, is a stand out Friends moment. Just because you don't like her for whatever reason, doesn't mean she cannot act. And how unpleasant to say "Nice to know someone else doesn't like her".
I think JA is a great comedy actress too. She might not have a huge amount of range - who knows? She does tend to stick to the same type of roles, but so do lots of actors. I like her a lot though.
I suspect that many actors are more than happy to do what they love and not necessarily have lots of recognition. Too much fame could be a nightmare, I imagine.