They were moving out before those rent increases. The problem is the kind of boutique retail people seem to want in cities isn't profitable; even the older midsized or speciality chains got edged out by national ones. This is kind of like wondering what happened to all those computer places back in the 80s and 90s that would build you custom PCs.

And HN did its part to kill it too. Can't have music shops when you destroy physical music as a concept; can't have bookstores when no one wants to buy books. Movie sales and rentals? Internet. Electronics? Online category killers. Second hand stores? Ebay.

The rent jacking up is an issue too, but even if it were lower, you still wont get businesses. There's been a big change in retail overall due to the hyperefficiency of the internet; the kind of stores that existed pre-net can't compete.