First of all, XTO Energy is a completely different company under the management of ExxonMobil than they were under Bob Simpson. Second, one could look at the parking garage as a temporary filler for the block until then need is there for an office building, or other use. I will agree with Renamerusk in that 640 Taylor is a better use of a downtown site. I would like to see something more on this block, also. However, it is their property, and they can build on it as they wish.
I, too, would like to have seen a high-rise Class A office building or mixed use development at this location. A 50-story tower would have been wonderful.
But, I think what happened is that the project promoters failed in their marketing efforts. Probably no fault of their own. I'm guessing that the downtown market demand has declined because of the Jetta project, the Sundance Square buildings, and other new office buildings downtown. If that is an accurate assessment (my anecdotal observation only), I suppose they could have put their parking garage project on hold indefinitely until they recruited more commercial retail or office tenants.
Then, again, maybe they need this parking garage as soon as possible for their employees and other tenants. Maybe some of the recent projects that eliminated parking lots (including the projected Jetta project) has created somewhat of a scarcity of available space.
As to height, I note that most of the parking garages downtown are in the 6-8 story range, while this one is planned for nine floors. Don 't parking garages have more height than other kinds of buildings because of higher floor-ceiling heights?
Renamerusk, have no worries about future skyscrapers in downtown FW. Eventually, the scarcity of available land, the narrowness of the tracts, and market demand will mean that vertical rather than horizontal construction is of greater cost efficiency. And, if one of our old towers needs to be imploded, the replacement project would have to be of sufficient magnitude in order to bear the cost of demolition, among other costs.