Why didn't they improve Animal Crossing's graphics?

Basically, because it would've been a LOT of work to remake everything in the game, and no, just improving things a little isn't viable.

Focusing on the fact that they left the models and textures the same is really emphasizing the negative. What would be preferable: for them to release the game on the dead N64 system for more cost with lower resolution and framerate and fewer features, or release it on the GameCube?

Alternately, realize what a great deal the game is. It's $50 like most new titles, but includes a free Memory Card 59. These puppies sell for $15 new separately, so it's like the game is $35. Even further, a lot of old NES games are contained within the game. Some are so rare you'll probably never get them, but considering other classics packs, Nintendo could've easily sold the NES games by themselves for full price. Even if we imagine them as being extremely generous and selling this fictitious NES set for $20, that would mean that the rest of the game would be 35 - 20 = 15 dollars. So break it down and you get a memory card for $15, a nicely priced classic games pack $20, and a somewhat improved port of an excellent N64 game for $15.

September 16, 2002