I tend to agree with you on that one. Further, the actual critic reviews I've read have not been that negative ... they were certainly not as enthused as the reviews for, say, Wall-E or Up, but the negativity has been nowhere near as bad as the negativity towards POTC or Green Lantern. The greater amount of negativity has been on this forum, mostly by posters who have not yet seen the movie. And mostly as a way of spitting bile at Mr. Lassiter or Cars or whatever other grudge they have to bear.
Will the movie bomb? I doubt it. As has been pointed out, the franchise has a pretty solid audience.
Even should the movie pull in lesser numbers than originally planned for, the first movie certainly has generated enough enthusiasm (not counting the haters on the forum, many of whom, I suspect, are just looking for a Goliath to throw stones at) to garner a park attraction. Carsland, after all, is based on the Radiator Springs of the first movie, not the world stage of the second.