Be grateful, EA's done a terrible job with the license. Buy a old Papyrus NASCAR PC title and have some fun.
I guess the sales just weren't there to justify it due to the lower installed base than the PS3 had, and the less EA Sports fans the console had than the Xbox.
Xbox isn't getting a new NASCAR game either. They're phasing out their support for the past generation in favor of Xbox 360 and PS3 development, the PS2 is going to get a port just because PS2 games can still be successful do to 120 million consoles out there.
I suspect Wii isn't going to get one because of the same reasons the GC only got a couple, plus the controls aren't exactly suited for such a game and EA wants to focus on next generation consoles as far as NASCAR goes, I suspect they're too cheap to downgrade a 360/PS3 NASCAR title for the Nintendo Wii and there's probably not going to be enough profit in porting over the PS2 game to a small market with a even smaller number of NASCAR fans.