I'm not expecting a major waterfront development with the scale and big-time density like this in Pittsburgh anytime soon (though I still hope we can do it someday), but the same principles apply from this project I'm currently involved with in Boston. See that the waterfront tracts are residential (with ground floor space dedicated to bar/restaurant), and one building on the marina being mixed use office/hotel/residential. The office buildings are situated behind the residential buildings, not on the water.
Lease commitments from various med-high to high-end businesses for the ground floor spaces throughout the development were contingent on the waterfront tracts being dedicated to residential. Initial proposals for one of the tracts to be office resulted in lease commitments from these dropping off by 65%. Why? Because they know that if the most valuable parts of waterfront tracts are dedicated to residential, it results in the overall development becoming that much more desirable to everyone. And the more desirable of a waterfront neighborhood that is created, the more people come to visit and return again and again to visit.
In the case of the SSW, putting a small office building on the waterfront and residential behind immediately results in residential units that are not as desirable as they would be if located on the water... and the overall success of the development as a destination in the city cannot reach its potential. Better residential = better neighborhood. It's as simple as that. At the least, I would like to see this building mixed-use.