Motion controls and button controls are not mutually exclusive. And buttons are essential for games that require more precise controls, in the same way that a physical keyboard is essential for writing long texts.
Having watched my children I must respectfully disagree. You need buttons because your hands are now wired that way. My little boys are happier with the sensitivity of a tilt. They were never wired to buttons.
It's pretty obvious that iPhone games designed to be controlled by tilt work well with tilt, it's not at all obvious that other genres of games work well with pure tilt controls.
It's also a bit premature to draw conclusions from kids at an age where their fine motor skills are still developing. They could be getting frustrated because pushing buttons is hard for them.
