Admittedly the released list isn't showing the new Mercs, so the E63 might fill the FR sedan gap so long as it's not the 4Matic model - amazingly, the XFR still hasn't been brought up to Premium status too. But yeah, I see what you mean; other than the historic oddities, the new cars seem to predominantly lie in either starter-hatch, hot-hatch, supercar, or race car categories. And those historic cars will probably not be competitive unless the tire model (and tire mods) are massively overhauled from GT5. Skinny old tires just won't allow for much.
Eh, yes and no. Admittedly we're the fringe, the hardcore fans who join communities online to discuss the game, when most never will. But I know I've been pretty satisfied with other games' car lineups, more so than GT5's (or 6's). GT has the wider range, but it's so scatter shot that there's too many significant gaps for my tastes, at least compared to the other games I play more often. The excellent track list for GT6 is far more impressive to me than the released new car info.