Players should be happy to get any number assigned to them and think about the front of the sweater (not jersey) instead of the back of it.
If it sounds too hockey and old-timeish, too bad.
As for this newer term of "self expression", do your expressing on the ice with your play, for the crest, without regard to a silly individualist endeavour such as a uniform number.
A true professional doesn't give a crap about what's on the side of the sweater he can't see.