The way I look at it, at least part of the reason is : The competition.
What I mean is that if they built a $15-25k rwd muscle car, its probably going to be full of cheap plastics, oversteer you into the hedge and get out-run by slightly cheaper Japanese or Korean imports.
Back in the older days, there were no VTEC Civics and Turbo'd Silvia's to compete against.
Basically, if its not priced/built to the standards of say a 350Z, its going to get out-gunned by the 350Z and then everyone will say its crap anyway