Actually ... not every kids' movie in the last twenty years rolls with the message of how you can be anything you want to be and to not let the haters drag you down. Some of the better kids' films in the last two decades deal with how selfishness and insecurity can lead you to do terrible things and make foolhardy decisions (Toy Story trilogy). Other films deal with the fact that people you care about can die (The Iron Giant). Still others run with the idea that being true to yourself can make you inadvertently betray the people you love most and put them in great peril (Brave, from last year no less). Still other films run with the idea that a child needs to learn to be less of a whiner, be willing to work, and consider the welfare of parents (Spirited Away by Hayao Miyazaki, to play a bit with themes). Sometimes kids' movies are about the fear and need for control some parents bring to the relationship they have with their children (Finding Nemo).
While I'm as skeptical as anyone about the cult of self-esteem in childrens' entertainment I think the average film critic may not be aware how diverse the world of animation actually is. In fact we've gone so far afield of the previously unbroken American custom of thinking of animation/cartoons as kid stuff there's a sense in which this criticism from Luke Epplin, sympathetic though I find it, may not quite grasp that we've got some more variety in narrative than, I dunno, some quasi-John Galt kid who is misunderstood and could do so many great things if parents could just get out of the way (that's been a template in Disney films since at least as far back as 1989 or so).
And let's cast about for more adult cartoons, like the animated film Persepolis. Marjane Satrapi wrote "Freedom has its price". It may be that the truly pernicious problem in Western kids' entertainment has less to do with the "you can be anything" trope as with the narrative shortcuts taken on the way to urging everyone to realize his/her inner awesome. There's a difference between promoting a right to a freely chosen path and promoting a right to a freely chosen path while remembering that it has a price. In grand theological terms it's easy to say that Someone else has paid the price for our freedom but in day-to-day life it can be easily forgotten that life is still full of opportunity costs and that to take one road you have to forsake others. If that is a lesson that even adults seem incapable of embracing in the modern US it would be no great shock to see that it is not a lesson we seek to inculcate in children. Just throwing that idea out there for consideration.