For all intents and purposes, Kid Icarus IS a new IP; his last outing was roughly twenty years ago, and despite the internet clamor most folks have never heard of him. Moreover, it's obvious that the new game has little to do with its predecessors: the gameplay seems closer to Sin and Punishment than anything else, which further clarifies how this game is for practical market purposes a new IP.
I think it was wise to tie the IP to the new system: it lets Nintendo introduce what is in essence a new IP while wrapping it in the shell of an old title which many of the hobby's most enthusiastic consumers (i.e. us) have not only heard about for years now, but with which they've been teased about for years. It's something of a win-win, really; make whatever game you want, while giving The Fans the game they've been hearing about.
