That's true, I'm not denying this at all.
What I was trying to say is: did this happen because of the huge install base of the PS2 compared to GX/Xbox or because developers were less prone to multiplatform development that is quite common nowadays?
it was because PS2 was both a good console as the others, it was cheap, and it had a strong headstart.
there was no strong compelling reason to chose xbox/gc over ps2 besides their exclusive.
edit:
This gen, xbox
+ was considerably cheaper than ps3, not the case last gen.
+ was released before ps3
+ has better online
+ had xbox as its predecessor with its own exclusive/fans
+ managed to get some early very good exclusive ips
+ was lucky fps/online gaming going to boom
+ developers needed to go multi to manage production costs
This gen, wii
- was on a league of its own
---
next gen
xbox
will be in an almost better situation as this gen
- losing some of its exclusives
- probably won't be cheaper than ps3
+ will come after succesful 360
+ has kinect
ps
will be in a worse situation:
- losing most of its big seller exclusives
- move didn't move
- not coming after ps2
Wii
will be in an unkown situation
+ probably cheap
+ coming after wii
+ nintendo franchises now almost as relevant as they have ever been
+ 3rd party support
+ all the control methods
? online
? graphics
? you are the controller (kinect) vs buttons
? abandoned hardcore, will they trust?