That's far from the only reason people were moving downtown. In fact, of the people I know who have moved downtown in recent years, none of them actually worked downtown. They simply wanted to be more in the middle of things. Its not like the downtown employment grew all that much in recent years while downtown housing units skyrocketed.
Rather than trying to incentivize antiquated workforce patterns, cities need to focus on how to continue this trend. Continue to develop downtown areas so they are attractive places for people to live with lots of activity going on. DSM doing things like pushing events like 80\35 and Oktoberfest out of downtown to water works park is probably the opposite of the move they need to be taking. Not to mention, when you get people downtown from living there and not just working there, you get business at a wider range of hours, not just over the lunch hour, which benefits downtown restaurants a lot more.