From what I've been able to follow, the commercial units were priced so high when they were finished at the peak of the boom that it was effectively impossible for a retail/food business to buy one and end up cashflow positive at the end of the month.
I remember someone here doing a show of the numbers on just how many cups of coffee that coffee shop that had been there would have had to been selling to make rent/mortgage, and it was just stupidly high compared to the traffic you would have expected for that space.