Because I do. I liked the "GTD"-style Mustang. It was good. And, more importantly, it was the only car in that range of performance the game had. A bit slower than GT3 - well, GTD. When (well, at this point, we can say "if", grin grin ) we'll be able to run multiclass races in Single-Player, it would have been perfect to mix with P2 and GT2, to remember to glory days of the Grand-Am championship. And now it's gone And in a broader sense, there's not much choices in GT cars now for multiclass (GT2 and GT3 do not work together IMHO) Or even to just...drive. There's no car under the GT3 class...(and no, FWD do not count!)
Well, since this year, GTDs are using GT3 specs, so mixing GT2s and GT3s makes sense (of course only on American tracks, like Sebring )