Seems simple enough. Write off the top 25 problems and let folks find work-arounds. (I avoid 625 East, for example). There's enough money for the rest.
Unmentioned are the problems caused by poor design choices and TxDot induced congestion. For example, many of the lanes are designed so that the tires pound on the concrete seams instead of having the concrete panel widths match the lane width. This hastens the need for repairs, funneling money into the pockets of the contractors, but greatly increases congestion from those projects over the long run. Exit ramps too close to the cross streets back up traffic down onto the expressway. Lanes that end just past an exit instead of making the lane an 'exit only'.
The only question in my mind is whether the TxDot engineers are incompetent, or corrupt.
Why settle for either/or? I say both.
Poor design is the cause of a lot of ills. I remember when they first started working on the US75 'canyon' in North Dallas. The first thing they did was close 2/3rds of the exits. Once that happened, and you didn't have people merging in/out every 1/4 mile (or less), the road actually opened up in a massive way, even with the construction going on. We've got the same problem where I live now. There is a stretch with 4 exits all bunched up, and even after massive construction, things still slow down on that stretch of road. If they'd simply close 2 of the exists, (possibly one woudl do the trick) traffic would fly. Unfortunately, local folk would yell bloody murder if they had to drive an extra 1/4 mile to get on the highway, so nothing will ever get done.