Interestingly, the excellent YouTube series Defunctland features Astroworld in this week's episode:
Its closure sounds like a prime example of mismanagement, lack of ambition, and bad timing. It was a really big and well-equipped park, but Six Flags couldn't afford to add anything to it, and as such it stagnated. And then they decided to demolish it and sell the land, in the hope that the cash injection would save the company. It evidently didn't work, and Six Flags met the same destiny anyway, only with one park less to show for it.
Astroworld did succeed for a while, though, and Houston still has no other park to fill the gap it left (I think we had a thread on this a while back?). Maybe there's hope for the future here?