Was learning how to use the VCR everything that is wrong with raising children?
How is the iPad limiting? Aren't you confusing the Apple ecosystem with the apps on there?
Give them a piano app and see them fail, Give them a drawing app and see them fail. Let them play some of those gravity games and see them explore and fail.
I understand what you are trying to do. I too am thinking (and overthinking) how to best allow my kid to become great. I see no problem in you doing it. I would encourage it. But you seem to be overthinking your principles.
But that's just me. My son loves hammering at the computer too. (He is working he says) but he also loves playing games and music on his iPad.
They aren't mutually exclusive. For a child the iPad is not a walled garden and if they think it is then just jailbreak it with them. Actually now that I think of it, that seems to be a much better lesson in teaching them how to become a hacker.