Well considering that Cars was one of their lowest grossing (Outside their first 2 films, when they were still a baby), and lowest rated, anyone who doesn't see that this is a marketing ploy is severely misguided. I equate it to Batman & Robin, where they ignored plot and went with "What kinda cool toy can we make?"
Sure, some people will enjoy it, but this is a huge step back for Pixar. If we use Rotten Tomatoes as a guide, this is their first Rotten film, and it's getting close to very rotten right now. In fact, all of Pixar's films have been 90% or better, save for Cars, which was at 73% (With the sequel at 30%). Pixar obviously has talent, with the ability to create a wonderful 3D world to immerse us in, and tell a story. Now they are going into sequel mode when the only film besides Toy Story that should have had a continued story was, obviously, the Incredibles. With Cars 2, there seems to be no progession of characters. Just a new setting, and new plot, with a whole bunch of characters (Especially international ones) to market it all over the world.