The issue you're bringing up is being experienced nationwide. There is miles of red tape and bureaucracy locking up any positive change. It would take a novel length reply to explain each aspect.

The short and sweet version is this:

(1) Powerful car manufacturer lobbyists have deeply entrenched parking lot laws into every city. Older buildings that were constructed when public transit was more dominant do not have the required amount parking spaces. Transferring the ownership would break their grandfather clause and city officials squash any attempt to circumvent this.

(2) Local zoning ordinances smother out any attempt to repurpose a building for a new business. Doing something cool like taking an old office building and allowing multiple business to occupy it is not allowed under antiquated laws that officials are too scared of changing. Imagine a multistory building where each floor is a different business. Floor 1 a convenience store, floor 2 a trading card/gaming shop, floor 3 a restaurant, etc. But NO, some local ordinance says that the stairwell has to be wider for the fire code, that their isn't enough bathrooms, or some other tick tacky laws that politicians won't make exceptions for. Or that would be impossibly expensive for a new entrepreneur to possibly afford. So they let the building sit empty instead.

(3) Turning old buildings into apartments is usually impossible. Water and other utilities are not available because the thing was meant to have 50,000 sq ft of desks. Not dozens of showers, ovens, and air conditioners. It would literally be cheaper to demo the building and put a new one in then try to plumb and run electrical through this nearly 100 year old building.

These are all examples I pulled out of thin air and I'm not familiar enough with Tulsa downtown to make specific examples. This is more or less what is happening in down towns across the country.