I actually agree with you. The Mk IV Supra and Original NSX Type-R as Premiums are needed. Both are landmark sportscars.
As Classic Super GT cars, yes, I agree. Go back to GT2 with the Kure and Zexel R33GT-Rs..... But I'd go further back to the Group A days. The:
Reebok #50 R32 GT-R
Calsonic #12
#2 STP Taisan
#11 BP Trampio
#22 Axia
#25 Zexel (1991 Spa 24hr winner)
#1 Unisia Jecs
#55 Kyoseki
could and should all be included. The basic body and drivetrain would be shared by all vehicles with livery and minor cosmetic differences only. Think of it as slightly more interesting variations on the Nascar duplication approach - that the same basic car midel can make several different vehicles. It's just that these can accelerate, brake and turn right too..... (tic) Seriously though, PD have access to the above cars in Japan at the Nismo Festival and at Nissan's storage facility at their disused Zama plant:
http://www.popularmechanics.com/cars/news/vintage-speed/4279549#slide-1
And while they're at it, make the Nissan Motorsport R32 GT-R that won the 1991 Bathurst 1000....
Premium R33 GT-R LMs 'Keep the Dream Alive', 'Clarion' and 'Jomo'
Premium R390GT1 roadcar (1997 redshort tail), (1998 blue long tail), and racecars from both 1997 and 1998 (short and long tail versions respectively).
Then there's John Morton's BRE #46 Datsun 510 1971-72 Trans Am 2.5 Challenge Series Champion. That's iconic and would get the American enthusiasts going too.
Hang on, I've now turned my post into a car wishlist. Sorry.