Unfortunately, not at all. We can all imagine another game with uneven quality of cars and tracks, poor sounds and AI, wobbly framerates, shaky netcode, and lackluster design of events and features.
While I'm sure we can all think of a better game than GT6, we can all also think of one that would be much worse. It's hard to make a good game, but it's not hard at all to take a decent formula and turn out a stinker.
Everyone hopes that it's not going to turn out like that, but the fact that after GT5 and 6 it's very much a possibility is what has a lot of people hesitating until more information is available.