Never buy a console for a single game. But do buy consoles that have games you want to play, provided you intend to keep said console and keep playing games. Personally, I would say the PS3 is one of the best consoles in gaming history when it comes to the depth and variety of games you can get on it.
I couldn't say FFXIII is worth buying a PS3 for. I couldn't say Uncharted 2 is worth buying a PS3 for, either, though, nor The Last of Us. But they are part of the bigger reason to buy the console: the solid number of incredible games that are definitely worth playing.