As a whole, we don't like smaller cars...you also forget that cars are ingrained into the American psyche as part of the "American Dream" and having a big car/truck is part of "making it"....Plus we also think that cheap gas or fuel is a god given right to us. Not matter if you think its right or wrong, thats just way things are here.
Personally I'm looking forward to how they go about making these standards...should be exciting and hopefully won't be as bad as the last time we went through this crap in the late 1970s and 1980's