If you google "BMW steering wheel finish rubbing off" it'll kick back 598,000 hits with everyone, from new M3 owners to i3 owners, complaining about the same thing.
If BMW were to admit that it is a manufacturing problem and covers the defect, they'd be in for a significant financial hit.
https://www.google.com/search?rlz=1C...67.8SJOH411O64