I do see the fun and understand the desire to change up the FGs a bit, but I have a few reservations, and as much as I like to play devil's advocate, I figured I'd throw them up for comment.
- I personally believe, with the amount of FGs to randomly fight, that a few easier ones is a nice reprieve from getting your arse handed to you from the last several matches by FGs you, or your deck, have a difficult/impossible time with.
- If the end game gets an overhaul we should look to expand its longevity by adding more quests or official events (such as incorporating WAR, WoE, or whatever, into the actual game). The catch 22 on making the end Ai more difficult is you get to a point it can't get more complex to upgrade without it OTK'ing you on the first turn. Then there's the issue that even if you do make it more difficult, not many will want to face off against it due to its complexity. Sure, you get to spin more or make more electrum, but how many losses would you have to suffer to get the reward?
- The casual or new player won't see this benefit for a long time. This really only potentially benefits players that already have a substantial card collection who will be able to tackle these new, harder FGs. I feel any overhaul of the game should be a benefit to everyone. Yes, those casual/new players will eventually get the chance to face off against the uber-FG, but it won't be for some time and many may feel discouraged since they still have a hard time with HBs/T50 as it stands now.
SG mentioned some time ago that splitting up the FGs into different realms was an option to consider. I think any endgame overhaul should consider that as a possibility. It sounds fun, opens up more quest ideas and could ultmately accomplish what this particular thread is suggesting.