Despite limited power and capabilities. It's developer friendly. Easy to develop for hardware and API. Nintendo became more friendly working with developers. Dev Units are cheap. $500.
Proper support 1st and third parties.
Marketed extremely well and very clear on what the system is.
The gimmick is a good one. It doesn't feel like you need some wierd ass controller or control scheme to enjoy it. It's a normal system than can also be taken on the go.