That's some slam dunk analysis. I don't know what two apartment buildings almost a mile and a half away from this site, and that are located next to an interstate highway ramp and a six-lane highway that soon becomes a limited-access expressway, has anything to do with the residential density of the Southbank.
There are 185 units at the Southerly, 147 units at SoBa, 243 units at Broadstone, 13 units in the Home Street Lofts (really 12 as someone owns 2 units that just haven't been joined together), 141 units in San Marco Place, 236 units at Peninusla, and 295 units in The Strand (in practice, 291 as four units are furnished daily rentals). There is a little more than 80 acres of undeveloped land on the Southbank. Street traffic counts are less than 50% of actual roadway capacity throughout the Southbank. There is less than 20,000 square feet of retail space in the Southbank, and none of that is clustered together. The proposed self-storage unit would actually remove existing retail space. By any stretch of the imagination, there is very little density for what is supposed to be an urban environment. Being a former Southbank resident, and whose mother-in-law presently lives in the Southbank, at no point did I ever turn to my wife and openly complain: 'when is all this growth going to stop... its just too intense here and there's just too many people walking and driving around, and I have too many dining options to choose from'.
I don't know why Vestcorp didn't build anything, but Vestcor didn't build a Lofts at Southbank project, as they didn't get LIHTC financing approved at that site. I actually answered that in another thread you started.