It's doable as long as the second slide pad is not required to play any games, required being the operative word. And if developers didn't use it (though I see no reason why they wouldn't), I wouldn't classify that as a blunder, just a waste.
A second slide pad should have been present from the beginning so we shouldn't even be having this conversation. I'm not sure what Nintendo was thinking. I believe Miyamoto said something about using motion controls for the camera but that doesn't explain why anyone wouldn't want the right slide pad anyway. Ultimately, I think a revision with an additional slide pad and other upgrades could work with minimal damage for reasons already stated. However, while the second slide pad will make some games better, it will NEVER make a bad game good. You can't save a **** lineup by throwing an extra slide pad at it.