whatever their reason is for doing it that way is probably what works best. they still sell plenty of tC's and s/c's since they've been on the market. people see "release series" or "special / limited edition" and think it's gotta be better than the original. they pull in the non-enthusiasts who are clueless to the real differences or who dont care cuz they have an individual #'d car.
that said, i would've loved to get the rs1 or 3