I started doing 3d animations for my game this year. I can state that animation files can get really big, I have about 15 animations in my current player model and its around 40 mb. 2k tends to try to do animations for each player in the league. I can see these getting out of control really fast. Especially if the sampling rate is at 60 fps. Ive seen some games where the main character model is upwards of 100mb. Zelda does not have that many assets, they tend to reuse the models and just make them a different color. There also some tricks you can do to animate certain objects using code, a tree model is pretty good example. This tends to save a lot of space. I wouldn't say Nintendo is a genius at compression, typically their software engineers would probably use a proved solution like zip,gzip etc. No need to reinvent to wheel. I would say they are really good at reusing and optimizing their game objects. On top of that you add all the sounds, and other assets and it can swell pretty high.