I was really surprised that they kept the Wii name, but it probably helps in brand recognition when people decide to buy the next console, kind of like calling it the PlayStation 2/3 or the X-Box 360.
I've gotten used to it being the Wii U. So long as it's good at what it does, I really don't care what it's called. I think Vita is an odd name, too, but again I don't care what it's called so long as it works.
However, I think Kinect was probably the perfect name for the device.