The reason to own more than 1 console, depends on the games available. I am an absolute crazy fan for The Legend of Zelda games, so the Nintendo console of the day is for me, as well as Zelda, you get Mario, Metroid etc.
The Revolution will allow you to download (for free or for a small fee) Older games from the previous Nintendo machines (except Gamecube games which are backwards compatible) which is a bonus for me, as well as the ability to play future Zelda, Mario, Metroid games...
But if there are games which don't get released for the machine you own, there is little alternative to buying that console. I wanted Shenmue II in english, as well as improved GTA 3 VC and SA, and improved Project Zero 1 and 2, so I brought an Xbox. Now that is an ugly huge machine, which I have sold to make way for the Xbox 360, which will have games like Perfect Dark Zero, Tomb Raider Legend etc, and will play older games (212 original titles compatible at launch, with more to follow) so getting the Xbox 360, with all its multimedia features is a good idea for me.
If there was a game, that I wanted which was Playstation exclusive, I may consider getting it, but buying a PS3 outright, is not an option as it wont be worth the money for me. And I have yet to find a Playstation Game which has compelled me to buy any Playstations so far. (the original PS is for my brother who collects old consoles, such as Famicon, American SNES, and Sega Dreamcast.)
I'm not getting at you. I am truly curious. How many hours a day do you boys spend playing games?
I'd be hard pushed to spend an hour on a games console.. I get bored so quickly.
Mental anxiety, Mental breakdowns, Menstrual cramps, Menopause... Did you ever notice how all our problems begin with Men?