I think the main reason for the big difference in the quality of the racing (or its closeness) is due to the tracks themselves. Put a slow corner (or 2 as they did with Donington) in ( 1 in Estorill) and you will ruin the quality of racing. Pity Dorna and riders reps don't do something about that as well as the safety issues.
However tyre issues have for many years made racing have different levels, - for years in the WSBK series Michelin would only give their good tyres to Ducati Corse or HRC, - so they got there just reward.
For me, - tyre brand makes no difference to the tyre I choose to buy for my road bikes and I really don't care who wins on what tyres although i wish Dunlop would invest in some proper baseball caps!
The one tyre rule in WSBK was good, despite the bull coming out of Laguna about lap times it really does not matter. - It was also ok when WSBK caved to the Jap factory pressure by allowing in 1000 fours ( although only an idiot would say a twin and four of the same capacity are equal), just a big shame that the Jap factories caved in themselves under pressure from Michelin and pulled out of the series.
Next year potentially looks good with GSE back in WSBK (as their MotoGP request for D'Antins slots got turned down), although on Hondas, - and that as this year will be an undercover HRC team.
