I think it has more to do with the specialty store concentration in MOA and the Southdale/Galleria area in Edina then the concentration of "wealth". If they were going for pure wealth areas, they'd open up a store across from the Minnetonka Boatworks
Or stick it downtown on Nicollet. Alot of the Apple stores around the country tend to be in higher end malls with large numbers of specialty shops. In MN thats MOA, and soon Southdale with all the renovations they are doing. The rest of the 'dales really don't have the high end draw that the other malls do. Besides, if you're just looking to buy a mac, wouldn't you be ordering it online anyways?
Brian