Ehhh. I think having to stop and think "do I really wanna spend a quarter for this" would kill a lot of the appeal of "oh man I have a few minutes time for DOMINION " for me. This payment model is not my favorite ever but I still vastly prefer it to per-game or per-month, and haven't come up with a better alternative.
Well, you would probably pay in Gokoins or whatever, and buy a bucket equivalent to a bunch of games only occasionally.
Also under my proposed model it would only be $0.25 per game if you always lost, and with a 10% rake you would only need a win rate of 1.2 to break even.
Obviously these numbers would need to be tuned, but I think it has potential.
But that's not all... beyond the amazing bonuses of having to deal with online gambling
you get
A community that goes to hell because, hey, money is on the line.
A strong incentive to play weaker players because hey then you're earning money rather than losing it.
A beginner unfriendly scenario where people (relatively) new to the game hemorrhage money.
and much much more... All for the low, low price of 25 cents a game!