it's probably not a big deal. the gamepad is like over half the cost of the system. if you were to brick and couldn't do the hard mod method, it'd probably be more prudent just to buy a new system. I'm sure the price of both would be nearly the same.
That's true, I see Wii U's sell for around $40 without a Gamepad on ebay frequently. At that price it's just less of a hassle to do that than to hardmod the Wii U and restore a backup. All the same, not even a problem. While one can brick their Wii U, as long as they follow the steps carefully when actually installing CBHC and the like, then there wont be any problems to worry about.