The purse has nothing to do with it.
Due to the schedule this year, they were throwing a bone to Texas and stuck giving them the ASR, and they probably knew there wasn't much hope for the race. So they came up with the goofy format to keep it entertaining. But why did they go with the low HP, high DF package? Why didn't they go the other way? Because it's irrelevant, the new car is coming next year and they would have nothing to gain. If they removed the restrictor plate aka "tapered spacer" and went with a small spoiler and soft tires and the racing was great, it would make them look bad for not doing this sooner.
But having this on a Sunday evening was the worst decision of all IMO. There was absolutely nothing "special" feeling about this race. It felt like everyone was just begrudgingly going through the motions.