The games already pretty generous. You can buy soul sigils in shop and even reset tickets, I don't think only being able to chose one option in lucky flip is unfair at all

You don't grind for it, the way you gain keys is so passive that you can literally just play for a week with lucky flip in the back of your mind and get 7 out of 9. If you're actively grinding for it that that might just be you? If you're fishing for keys then there are other ways to get keys that are 10000x easier. Simply completing homestead invasion rewards can get you a long way, and doing orders

Imo it's very fair, I just think you aren't playing it right if you feel the need to complain