Price...I too had a PS2 that I played a lot and enjoyed and come the new gen (last gen) I knew I either wanted a PS3 or a Wii and with the price difference, it was a pretty easy decision for my Mom to make. I did end up getting a PS3 a few years later after some price cuts but Wii was my main last gen ^.^

Well... I grew up with a bunch of different consoles, but PS2 was the main deal for me, I still have my PS2 and games.
However, when deciding on whether to get a PS3 or xbox 360, I chose the 360 because of Dead Rising and I wanted something different... Plus, I believe it was cheaper when I got it.
I sort of regret that decision now, I wish I had a PS3. The next console I buy will be a PS4. But I'm more of a PC gamer really.