It certainly has not been 2 years. I just don't do FPS as much as strategy (Civ 4 for example). The last FPS I played was either FEAR, Area 51, or PREY. Prey ran totally fine with maxed graphics. Area 51 or FEAR I think I had to back off just a bit.
FEAR - Released 10/17/05
Area 51 - Released 04/25/05
Prey - Released 07/11/06
No offense, but regardless of when you bought them, the last FPS's you played were all released 2-3 years ago. The only one of those three with a fairly advanced engine for the time was FEAR, so it would make sense that thay might have been the one you had to tweak a tiny bit to preserve framerate. And FPS's generally have the most taxing system requirements, compared to RTS's or RPG's.
The rest of your points are mostly correct though--PC's as a platform offer a lot you can't get on your console. Like you said, you can't type a paper or go on YouTube on your Xbox 360, and the thought of playing something like StarCraft with a PS3 controller breaks my brain.
The only other thing I take issue with is your idea of economy, and the idea of bringing in utility to a gaming discussion. For someone who just wants to play games, and already has a computer suitable for web browsing and office work (i.e., every single person on this forum), consoles turn out cheaper in the long run. This is a gaming thread on an internet forum, so I'm going to assume we all have PC's and want to talk about games. So, I'm going to ignore your question about how many consoles can you do work and school on, and focus on how much gaming fun you can get out of $1500 over seven years:
01/26/00 - PlayStation 2 released for $299
11/22/05 - Xbox 360 released for $399 (Premium edition)
11/19/06 - Wii released for $249
11/17/06 - Playstation 3 released for $599 (60GB premium edition)
So, for $1546 you could have had the most popular console from the last generation, and every single console from the current generation. Console generations cycle every five years or so, and the effective life of a console (the time where new games are still being released for it) extends about another two years after that. If we assume those figures hold true for this generation as well, your PlayStation 3 will still have new games coming out for it in 2013. The first console on the list was purchased in 2000. So, you're looking at thirteen years of gaming, almost double the seven you got out of your PC. Even if you declare a system dead when it's successor comes out (which isn't true), you've got a good 11 years there from the launch of the PS1 till the "death" of the PS3.
And, all the figures I gave were launch prices, so really they could only be compared to buying the best and fastest video card right when it comes out. And if your PC cost $1200 originally, there's no way it had the best video card at the time. Most people never buy the newest, bleeding edge video card because they're all $300-$400 on release and have been since the Voodoo3d days. People buy the value cards from the current line or the cards that were bleeding edge 6-12 months ago. And if you wait twelve months, nearly every system comes down in price. (The same thing goes if you buy the Core/20GB editions instead of the premium ones I picked out.)
A frugal gamer, who's willing to wait for the first major price drop, will save on average $100 per console. More if he goes for a basic system. And we've got four consoles on my list, so that's a savings of $400. With an extra $400, you could have bought an Xbox after the first price drop (to $199) and a GameCube at it's launch price.
And in that case, for $1550, you'd own every single console from the last and the current generations. Not a bad deal at all.