Despite its history with the Wainwright Building and The Gateway Arch, St. Louis seems to have always had an aversion to building tall.
The anti-tall NIMBYS in St. Louis have killed a number of projects over the years. And many of the killed projects wouldn't have even reached 500'.
The second tallest building in the 2000's - after the Eagleton Courthouse - to be built was The Plaza in Clayton (409'). NIMBY's killed the original plan (below) because they feared a "shadow" would be cast upon their neighborhood and they feared the condo units wouldn't sell in a taller structure.
Also, St. Louis' bigger companies do a lot of build-to-suit projects in far-flung suburbs that frown upon height - Des Peres, Town & Country, Chesterfield, Maryland Heights (to a lesser extent) and Creve Coeur.
Personally, I think, the exception being Chicago and it seems Minneapolis, the Midwest has a mindset that it doesn't build what it doesn't need.
Other regions - particularly in the South - such as Houston, Atlanta, Charlotte, Austin, Dallas etc. seem to have more of a "build it and they will come" and risk approach to building.
Plaza in Clayton, First Proposal
Plaza in Clayton, Second Proposal
Below was the final result because of NIMBYISM.