Re: steering wheel controls, you don't think it's an improvement to be able to keep your eyes on the road and your hands on the wheel?
Re: steering wheel buttons in general, it depends on how they're implemented. If you take an old idea [1] and provide tactile locating then it is easy to learn. If you can reuse a common paradigm (a knob for volume) there's no learning required. The steering wheel also is already a busy place - you have two or more stalks nearby, sometimes cruise control is part of the steering wheel buttons and even if not the amount of space means you are forced to provide a subset of functions. A stereo with tactile-marked buttons and knobs is known to most drivers via other paradigms and is easy to swap between cars.
For everyone else, we've had automatic cars for forever. There's also a video online of a man with no arms who learned how to drive their car without them.
Edit: changed to be specific about the one hand on the wheel.
Consider that at a critical moment the difference between moving a thumb and moving ones whole arm and hand could be the difference between life and death.
EDIT: fixed typos