Slate has an article this morning noting that Apple retail sales are doing really, really well . Not just "good", but "twice as good as the 2nd place finisher", in terms of sales per square foot. (2nd place was Tiffany, 3rd place was lululemon.) The author - correctly - notes that when your revenue is that far out of line with the rest of the industry, you're leaving money on the table. Add a bunch of Apple stores, and while the average revenue per sq. ft. will drop, you'll sell more stuff and make more money overall. But Apple is a unique case. And aggressive expansion into new markets - both in retail and in low-end devices - would cause long-term damage the most profitable brand in tech.