I'm not going to stand up for EA, but when you step back - it all comes down to money and licensing.
Ferrari, Lamborghini and Porsche all have licensing and game deals with other game companies. If I'm not mistaken, Sega's got Ferrari, Nintendo has Lambo and EA's got Porsche.
I said this a loooong time ago in another community, but be happy for what you DO have instead of raining a hate parade for what you DON'T have. Support GT in all it's glory and when the above contracts run out, they'll want to be part of the best (IMHO) racing franchise out there.