Actually, I've always thought that the humans were more of a focus throughout the entire movie than WALL-E and EVE, though it doesn't always appear that way. The second half was built up by the first half, as it was established in the first half just how ****ed up Earth has become due to our own incompetence and uberconsumerism. The second half further elaborates on how we've ****ed up, both mind and body. People like to assume that the WALL-E/EVE love story was just shoved to the wayside because it's focused on SO much in the first half of the movie, but I feel that the love story was the build up and the backdrop to the real main plot of the movie: The human race seemingly screwing up Earth beyond repair due to our own incompetence and materialism, and EVE's discovery proving that Earth was not beyond repair and was salvageable.
Yeah, I've watched WALL-E a LOT.
So what you're telling me is that EVE and WALL-E found love in a hopeless place? Beautiful.
But seriously, going off what you said, that would make it true what they say, that the character that isn't there is always the most important one. The humans screwed the Earth over beyond repair, and it would have stayed a desolate wasteland had Eve not discovered Wall-E