Re: WALL-E (Pixar 2008)
I love all of the Pixar films; some more then others, sure, but the thing I love about them most is that they have a relatively simple, but very heartfelt type message to them that manages to ring "true". We took our boys to go see a lot of animated films over the last few years, and in some (I'm thinking like "Shrek") there are always moments geared to get a different kind of a laugh that have my wife & I squirm a little, the message isn't as straightforward (and even when it is it hits you over the head like an anvil)...
Yesterday, we took the kids to the grandparents for Christmas, and there on the set was "Cars". All of the kids, 4 years old to 14 years old gathered around and were sucked in; while "Cars" isn't my favorite, the end message of the movie was both clear and yet fun that I never once had misgivings about what was on the screen.. and the end, which was a pretty good metaphor for friendship, sportsmanship, and responsibility is something even a five year old could latch onto.
That's the thing Pixar does better then anyone else. Outside of the fact that the animation is stunning (and Wall*E looks that way) it's as though they've realized: you don't need to make a story convoluted or muddy.. it can be the same basic points people have made for years.. but if you do it better then they did, in a way people want to watch, then people will absolutely buy in.
That's why it worked; it's why Incredibles as a "family who comes together" story works. I really enjoyed Ratatouille as an "Overcome your adversities" type story.
I love the new trailer; it's an absolute proof-of-concept for what can happen with animation (the spray from the fire extinguisher is incredible!), but with Pixar, while the animation has been better then anyone else, it's that the story is something I'd sit down with my kids with at any time with no reservations.
Other animated flicks should try and figure that out. Come up with something that can draw a tear from the parents at the end.. not because we're worried about what's in it, but because the message says what we want to say, and you've got a winner

Edit: And I will say now, as time has past, "Toy Story 2" has slowly risen up my list of "Greatest Movies of All Time" for it's ability to capture so many both adult and children's emotions so effectively; complex issues like losing love; growing up; remorse; regret; the desire to feel important; there are very, very few movies I've ever seen that manage to nail the human experience even half as effectively. This is the only film I've ever seen in my life that not only made me cry, but I absolutely thought that I was going to need to leave the theater to compose myself after "When She Loved Me" happened; what kid can't relate to a toy they loved & outgrew; and what adult hasn't been through a relationship that, even after it was gone, missed that connection..
As long as Pixar keeps that kind of focus on the storytelling, then they always have my money at the gate.