I've been told the DCAU team was actually asked about the movie at a panel they did with Kevin Conroy. Must've been awkward when he shot them that look of "what?" haha.

Also, it's not computer-generated as much as inked. With animation these days, that's how it works. The animation itself is still hand-drawn, but the coloring/inking/finessing is done on computers. Except for with vehicles etc. (which often end up complete CG, and this is one of my ONLY complaints with the direction animation is headed in.)