Tathanen
Get Inside Her!
It's conceivable that they are thinking "SD cards are too small." With that one game (was it Tekken?) weighing in at 17GB, you couldn't even fit two of it on a 32GB card. 3DS and Wii don't have that issue at all. Thus, with the Wii U here, they think of the SD card slot as "for media," and have it up in the front for that reason, easy in and out for pictures, music, video, etc. And your more permanent USB storage stuck in the back, with its far larger capacities.
Just a guess.
Just a guess.