are there some numbers to support that? I mean, f.ex. no of macbook pro and sony bravia or xbox sold in the supermarkets vs sold in brands' stores? I always get the feeling that such stores exist to keep appearances and attract new customers, not to work as a main selling point. selling 20 laptops through bestbuy is probably way cheaper and quicker than selling 20 laptops through it's own store.
It's important to keep in mind that going into retail looked absolutely ridiculous when Apple announced their first retail store, for some of the reasons you have enumerated. Gateway was what people thought of as a computer retailer, and they were dying. Execution matters.
I wonder if your store was average for the AAPL universe.
http://allthingsd.com/20120323/best-buy-is-selling-nearly-as...
As far as laptops and computers go I don't know why it'd be cheaper for Apple to sell them through Best Buy. The prices are rigidly controlled and so their margin has to be lower for other retailers then when they sell direct.