Again, we've completely lost the understanding and importance of public space in our country. I can't believe anyone would argue for a city full of parking lots and slight convenience over the richness of a vibrant urban city.
It's a failure of our country's zoning codes.
You're making the assumption that if you zone for it, you'll actually get it--rather than getting developers to simply walk and leave the dilapidated, older structures in place.
If the economics of the project could not support another Arena District-scale project, that can't be blamed on NRI.
I'm not averse to changing zoning codes, but they always have to be done with a focus on the fact that developers have the right to not develop, and at the end of the day, it's their money on the line. Aesthetic preferences need to be tempered by that reality (as well as the acknowledgement that if those aesthetic preferences were actually widely held, the economics of the project would not be infeasible--which should send a message regarding just how widely held that particular set of aesthetic values is).