It's all preference. I know a lot of people who don't use it and enjoy games perfectly fine, I also know people who need to use SSAA (which is very taxing) in order to be happy. Me personally I'm usually happy with 4x MSAA in most games, but there are some games where i just require SSAA (games usually with a lot of foliage).
I do play same games with AA off or MSAA 2x, that require absolute screen clarity, such as FPS games.