Mini's for mages also might make (for example) a new player playing someone who has one feel more intimidated, and could possibly lead to a less enjoyable experience than otherwise would have been had. (Or maybe the mini would be a cool thing to see, and encourage the new player to get one...?)
Overall though, I think that providing the minis in a boxed set would be better than selling them separately. Everyone would have them, and there would be no social stigma for not having one. The downside of that... it'd never happen. The price of the boxed set goes up, and no (or very little) extra revenue comes in from the sale of extra minis.