The most obvious critique in the movie is the environmental statement. In the movie, the Earth has become a barren wasteland, where not even plant life can survive. In fact, humans need to go live in space, because, Earth is so destroyed. This devastation is obviously caused by human endeavors, with mountains of trash just lying around. The obvious point being, that humans are currently destroying the Earth and something needs to be done.
The second critique that the movie is making is the corporate nature of modern society. We see this with the Buy and Large corporation in the movie. This corporation has become so large in the movie, that they are the only corporation and the only government. The critique of this being, that we are placing to much power in the hands of corporations. We see the distrust of corporations in this movie with the abandonment of Earth by the Buy and Large corporation. Also, there is a quote in the movie where the Buy and Large Corporation says that if you buy their stuff, you will be happy. In the movie, it is the captain of the ship, we can call him the beneficial dictator (kind of like the U.S. president is becoming).
The final critique of modern society in this movie is the distrust of modern technology. This can be seen in the dehumanizing nature of the ship AXIUM. In this vision of the future,people don't talk in person, don't see the outside world, and don't even walk. They are able to achieve this only because of the technological wonder of the day. Because of these, they are not even expected to think! While the movie does provide hope, with the robotic characters of WALL-E and EVE, they are only providing hope, because they act like humans.
Combined, these three critiques of modern society, and the ridiculous extension of them into a possible future, leads us to a world where no one lives on Earth, people don't seek to one another, and robots command our lives. If this is not a happy vision of the future, I don't know what would be.