I'm aware of their reasoning, however it all depends on how you drive the car. I'm not trying to pull better track times with my GXP, I drive to work and to pick my kids up from school.
So 18X8's with 255's are exactly what I'm looking for, and if I do say so, look much better than the 7" rims in the rear. It's all in what your needs are. Just my $0.02.