It creates multiple places to look for payments. Also, if the price is 0.99 vs 1.29 I would feel bad if I opt out for 1.29 with Apple despite the fact that 0.3p isn't changing anything for me but I would feel obligated to enter CC details to get the discount(Yes I know it's not logical but Humans, Aye? If people were logical half of the economy wouldn't be around). It's a friction I don't want to have in my life.

The ideal solution for me is, Apple Pay being an open protocol and I can add payment methods to Apple Pay, can track all payments from a single UI. Then I would be O.K. with being offered %30 discount if I pay with "Epic Card" payment method(form the same payment UI).

You would feel bad because you would know that Apple isn't providing a service worth 30% of the app's cost, leaving you feeling cheated.

Not at all, I wouldn't care who gets the money. Often company structure and relationships are complex and many times people who boycott a brand end up buying from the brand owned by the same company.

More importantly, It's a well know that people in the game industry are overworked and underpaid and it's not because of the Apple's cut. I don't know about the situation in Epic, but if it happens that Apple lowers the rates most certainly the difference will go to C level executives(that are not underpaid already).

If Apple gets the money, they at least will pay a decent salary to their people. The game makers can consider cutting bonuses if the money is tight.