How is this an opinion? It's simple logic. If Nintendo had had a better idea, they would have gone with that. By necessity, whatever they do, they do because they don't have a better idea. This is true of everyone, ever, doing everything. They went with motion controls for Wii because they didn't have a better idea. Sony made the PS2 a DVD player because they didn't have a better idea. Sega dropped out of the hardware business because they didn't have a better idea. Victor Hugo wrote Les Misérables because he didn't have a better idea. If he'd had a better idea, he would've shelved Les Mis and written something else instead.
So yeah, the GamePad was the best idea Nintendo came up with, unless someone believes they are deliberately sabotaging themselves by coming up with better ideas and saying, "Nah, let's go with the one we don't like as much instead."
