I think Chris wanted to not have to ban any car from the series, and let a car enter if at all possible. The RX7 can be slowed down by not allowing it to run a rear wing, and that results in laptimes being about the same as other cars. So really there is no problem there now. No-one's forcing anyone to use any particular car.
Personally I don't care what car I drive so long as it's not the S2000 (That car handles so badly I can't be arsed to try and sort it out). I would use the RX8 as it's (in my hands) the quicker car, but the RX7 without the wing now is quite lively and fun to drive.