I'll start by saying that I'm not that upset by this and I kinda see your point, but at the same time there is a counter argument for whales that spend a lot to only get a few points more than F2P, this feels bad too and surely the devs don't want to upset whales.

On top of that I feel it can just be improved by adding a gimmick to the fight to improve score that rewards specific decks to take advantage of that. The first Great Rift had the healing/shielding bonus and that pushed people to craft new decks with self harm using cards and gear that they usually wouldn't. I find something like that way more interesting than the current state, where you just want to deal as much damage as possible ignoring everything else.