I can only say what I have learned from my experience with art school (Ringling), but its a heavy CG school, so it might help you. I was told when first applying (2012) that when looking at a portfolio, and looking at animation, they're going to look at it with a very discerning eye, and hold it up to a relatively high standard (probably the quality of their current students), so in most cases they don't recommend putting cg in a portfolio just because it might knock down your overall quality of your portfolio, because of, well, common mistakes such as splinyness and fine tuning problems that are hard when you first start CG animation. Another reason why is that they want to be able to have you at a blank slate in regards to CG animation. They want to teach you the way they want to teach you with no deviation (even though each prof. has a different style of teaching, whether it be straight to spline, or stepped, ect.) without having you unlearn things. Ringling in particular has a very strict mindset of this policy, so it might be more lax with other schools. The third thing is that, if you put animation in your portfolio, and its very good, they're going to wonder why you're coming there in the first place, and they might accept you, but there might be some questions raised about why you aren't looking for a job, or something (this is honestly just a guess, take it with a grain of salt, but I feel that they would question it a bit, even though it might not affect their decision). As far as other CG modeling and other digital work goes, I'm not sure about how they would feel, as a lot of times there is only one teacher in the section that knows in-depth knowledge on those subjects. The tried and true excuse that they give is that they want you to keep focused on your foundations, but honestly it is so helpful to know cg before you dunk your head in, especially CG animation. Ha, my first semester I struggled with animation so much, I didn't even know what key poses were by the end of freshman year, so it does help to have prior knowledge even though they say its not needed.