Nintendo didn't want to pay for Rare anymore, because Rare was being wholly unproductive. Nintendo sold their shares of Rare stock, and MS bought them. It was Nintendo who got rid of Rare. Just making that clear.
Anyways, I am both a Zelda and a Star Fox fan, so I thought I would comment on why I didn't like Star Fox Adventures.
Zelda always rewards the player upon completing a quest. You gain a new ability, more money for doing god knows what, you get to play a fun minigame, you get another heart on your lifebar, etc. You always feel rewarded is the point. There's always a reason for doing what you are doing, and if you don't feel like it, you can always do some other sidequest to increase your power. You always have a choice.
Star Fox 64 is just simple fun. You are in an arwing, and you shoot stuff down. You are rewarded if you are able to fly with precision, and shoot down the most bad guys. There's a real sense of skill involved if you do well, and if you get a whole whack of kills at the end, you feel good, and you will no doubt brag to your friends.
Star Fox Adventures.... The graphics are good, gameplay is solid, however.... there is no reward for doing things. There's always a quest in front of you that you know will suck the life right out of you. You know that when you are done that quest, another will be waiting for you when you get back, with little more than a "good job, but...." waiting for you. There's no character development, and they insist on annoying you with the most annoying sidekick they could find. Navi might have been annoying, but never as bad as Tricky.