I think the only reason of doing 3d animation photorealistically is to demonstrate that it could be done. IMHO the closer an animated movie looks "real" the more it loses its appeal as an animated film. IBeowulf and Gollum from LOTR looked very real but there were tells that still made them look and act CGI. I think that we will come to that point that it will be hard to distinguish a 3d animation from live action. And when that time comes, what will be the point of doing a 3d animation that looks live action rather than a live action with CGI elements when you can't distinguish both from each other. I guess my point is keeping a 3d animation cartoony is not a bad thing.