but there is another possibility as to why the japanese aren't sending us decent sports cars anymore.
what if it was because there are so many posers who only buy baseline models and "pimp" them up?
why should Honda send us a Type R Civic if all most of us needs is a DX Civic and a bodykit?
I can see what you're getting at, but it's very unlikely. The more probable reason is the massive stack of rules and red tape they'd have to fight their way through to bring stuff like Type Rs to the States, where different safety and emissions regulations are commonplace. The trouble then is being able to sell enough to justify the cost of all that.
That's Type Rs in particular though, since you mentioned it. The main reason is that there's no such real thing as a Japanese sports car market anywhere at the moment.
I've been racking my brains to think of all the proper, ground-up sports cars the Japanese produce at the moment (as opposed to sporty versions of normal cars
a la Civic Type Rs and Sis). I can come up with the Nissan 370Z, Mazda RX8, Mazda MX5, higher up you've got the Nissan GT-R and much, much higher up the food chain, you've got the Lexus LF-A. I'm not including Infinity G37s and the like (plush sporty coupes) because they're more luxury cars that have a naughty side rather than actual sports cars.
The Lexus is impressive, but also stupidly expensive and very ugly (IMO). The RX-8, GT-R and 370Z are all great, but not necessarily affordable for young people, and the MX5
is more affordable but some people would want higher performance.
I don't know if it's just me also, but is America really warming to the NC MX5 or not? Looking around the internet I don't really see a great deal of support for it like you see for the older models.
So the USA does get sports cars from Japan, but they aren't really as affordable as they once were. There's nothing along the lines of the MR2, for example, which would give the MX5 some much-needed competition. Nissan were threatening to build an MX5 rival for a while too but I reckon the international economy problems killed that one off for the time being.