I'd like to see and Amiga-in-a-joystick too. Not because I'd use it as such....but I'd hack it back to a real, usable Amiga like with the C64DTV.
There's nothing wrong with a joystick type device. It means mass production, mass distribution and cheap prices. It would essentially mean a re-production run of an A500 (like the 64DTV was practically a re-production run of the Commodore 64).
It would also mean the developer (Jens, etc.) could actually make a profit on his/her efforts....profit means the ability to do further development on future products.
Also, an Amiga on a joystick doesn't automatically mean that there would not a be a "larger" mini A500 system released, that would be more computer-like. In fact, the success of a joystick type device would only increase the likelihood of such product being made.