3 reasons actually:
1. money...obviously. i plan on getting a job soon though. even then most of that money will go towards wii games.
2. time, i have a depressingly long backlog of games.
3. i got these parents that seem to hate the idea of me having more than 1 system. even if it is my own money.
HOWEVER, i am looking at a 360 later this year since i may have the money, regardless of my parents or my time. though i wouldnt spend as much money on it as my wii, i have some games ikn mind that im just iching to try, especially since my PC graphics card sucks.