It's rumored that the reason why it wasn't added to begin with is because Miyamoto voted against it. I couldn't find any proof of it, but here he explains that "it's common to use your finger to play" and he feels the gyroscope would be more effective for camera controls than a second nub.

Polnareff, I think the hate is pretty high, if you go to the comments on any article about it EVERYONE is freaking out while a few are still stepping in to defend Nintendo. I tried to add a positive spin to it because it's gotten pretty cliche to second guess every move they make by now.

IMO it maybe should be less. Unless there is a full redesign, this could remain simply a cool add-on for games like Monster Hunter that really need it. Honestly the DS didn't need one, a big part of its appeal is its RPG library and if I ever get a 3DS it'll be for those kinds of games, which don't really need a second stick.

If the full redesign does come, Nintendo's probably going to lose a lot of support from those early adopter who already got shafted on the price, who will now have bought a "test" model.