I think people underestimate how expensive the parks are to run and how little money they make from extending hours.
The obvious solution is to come up with ways to make money from guests staying later... Ya know, with appealing dinner? And they sort of did that. Sort of. I feel like thats kinda what Roller Coaster Restaurant was about. I think that's what Chessington's Aztec Restaurant was about.
Problem is, I've been to Roller Coaster Restaurant, and I won't go ever again. And... It's a miracle if Aztec buffet whatever it's called is even open. I want to eat there because I know it's pretty good, but they make so little effort communicating to guests that it exists and they can use it that they close it off peak due to low numbers. There's no reason why that place shouldn't be fully booked, constantly.
The thing that BAFFLES me is that if you go to, just, for example, Hansa Park... You have decent food, affordably priced. Down the bloody road at Merlin's Heide Park, how's the offering? Well, I had no desire to eat there.
What we need is a culture of guests behaving as they do at Phantasialand or Tivoli/Bakken, where they just come and hang out and eat and be merry. But the experience, the price and the quality HAS to meet that, and they just ain't even close.