At the time of its release, the manner on how it they’d marketed that was confusing as they showcased the Wii U gamepad as if its a portable console (its not) since its rather the main controller for the Wii U console. I was in high school when the console was first revealed, my reaction to that was “WTF?” as I thought the gamepad was portable, as the ads often flex that it can be (or the way they showed it came off as that).
It’s not just the name. For many the tablet functionality didn’t click with them too. Any casual (non gamer) owner of a Wii didn’t have any reason to buy a Wii U. They were happy with Wii Sports and he controls. And hardcore gamers wanted to have something normal they can play games on it, like the other consoles have it. The tablet looked like a pointless big device, instead having a normal controller. Name was a problem too off course, but it was more than that.