I think the GP series only works when there's more than one rider competing for the top prize, look how good the 2021 F1 season was and how dire it's been since then with the domination of Verstappen. Same goes for Speedway, pretty boring no there's no real contender to Bartek. At least back in the day of TRick's dominance he had real challenges from Gollob, Crump, Pedersen, Hamill, Hancock etc. How good would it have been to watch Nielsen & Gundersen battle it out over a GP series!
It's all about jeopardy, Bartek doesn't really have any, he can miss a GP and still end up winning, a one off final adds that jeopardy, one rash move and you're toast... assuming you've even made it through the qualifying rounds. Same with the GP series, if you've got a close challenger, have a bad round and you're toast