First, you guys know it was Konami itself that came up with the refund system, right? If the refund was going to be such a determent to banning a card, why would they come up with it in first place? They could very well not give anything when a card is banned.
Second and most important, as greed as Konami is, it knows the real money comes in the long run, sometimes you have to lose in one trimester for the sake of the longevity of the game. And it's definetely not sustainable for the game to not ban URs, it will just break with how much powercreep will skyrock.
Seriously, try to actually imagine the mess this game will be in even a year from now if they never ban any URs... All the new op cards combined with the current op cards... not banning URs is a good way to make this game won't be around by 2025, and Konami knows that very well.