Yes, you can surf in the internet on those things, why not? It's not as comfortable as on the PC maybe, but lying on the couch in front of the TV and surfing a bit is not bad at all.
Plus, I tried to make clear that a modern console is more than just a gaming device - even if you have a PC.
Let's assume your PC is in your office room and your TV is in your living room. How do you want to watch your movies then? You need an extra device in order to stream from your PC for example... or you need a DVD player or - and that's the best reason for a PS3 - a Blu-ray player. If you have a modern console, you can use it as a media center in your living room via network connection to your PC... plus don't need a standalone DVD or HD-DVD/BD player.
And yes, no need to discuss about personal tastes... but playing Gran Turismo or Little Big Planet for example on the PS3 is quite an experience which I can't get on a PC. So those would be two examples of good exclusive games on a console.
To make it short: Every system has its advantages. Most people have a PC and many need it anyway (for work for example). But I don't see the reason why to categorically say no to consoles... you can have both and you can have fun with both. The only aspect is money in this matter and honestly, Xbox 360 and PS3 are not that expensive anymore actually.
