I understand the disappointment over the lack of GamePad control, as it seems like a pretty serious oversight, but... to be honest, I still think it's a pretty cool feature to have (and I'll still hold out hope that we get GamePad -> Classic Controller/Gamecube Controller mapping someday, if possible.)
I guess I'm just sorta viewing this as another one of those "Oh, it can do that? That's neat" features that Wii U seems to build itself off of. Like, it's certainly not something everyone will use, but it's still a kinda neat thing to have. Maybe there are people out there who want to have Brawl or Mario Kart multiplayer sessions somewhere without a TV (an unrealistic and rather silly scenario in which they'd gather around a tiny GamePad screen, but I still think it's conceptually interesting.)
Still, I don't really mind propping my GamePad up on my desk or laying it on my lap and playing some horizontal-Wiimote games, so I'll just say I'm glad this update exists, but would still like to see more from it in the future.