First of all ps2 came out in 2000 so 2001 was its second year while ps3 came out in 2006 so 2008 is the third year. Ps2 sales for its third year almost seem unreachable by ps3...ever.
Reguardless the reason Sony won with ps2 and ps1 is because of third party support. Saturn and N64 never got it and GC, XBOX got a fraction of what the ps2 got. PS3 is on the other side of the fence now with 3rd party support.
Also, rarely does the most powerful console win. Master system spanks NES when it comes to specs, PS1 was not as powerful as the saturn or n64, PS2 was the weakest link last gen. Snes is the only one I can think of and the only reason it won is because sega didn't know what it was doing with the whole 32x, sega cd, saturn fiasco.