Everybody's talking about the anti-consumerism, anti-corporation message and all that, but one thing that I started thinking about today is that basically the people are ruled by the robots. But instead of "Ooooo, humanity is enslaved by evil robotic overlords!" ala The Matrix, the robots are just really, really, really nice to the humans. So nice that the humans basically voluntarily agree to give up their free will and humanity and live in their own little virtual world while the robots do everything. Wall-E, because he's lived all his life among the remains of humanity, is the only being left that still knows what it is to be human, and so he has to restore the people's humanity.