A tablet without pressure sensitivity would suck, but it's better than trying to draw with analog sticks, by far! I think a Mario Paint type app could be very cool paired with a suitably large storage device...Nintendo put forth the idea with the 64DD that you would be able to create graffiti, faces, and other texture graphics for compatible 64DD games using Mario Artist. I loved that idea, but I always felt it would be incredibly awkward using a controller. (Edit: and then Nintendo never really delivered on it anyway, of course.)
Still, with a mouse (or stylus) I would have created dozens of patterns for Animal Crossing by now, but it's too frustrating to do with the analog stick; I think I've made about three patterns.