There's what's legal under the current laws of the countries, and what I think is in the good spirit of things.
There's three things going on:
1. The intellectual property, the game, its mechanics, how they work, what the cards do, all that jazz.
2. The paper, cardboard, and other logistics involved in producing the board game.
3. The coding, maintenance, and upkeep of the digital version of the game.
There's legal things you can do that are not in good spirit. You can make your own set of dominion cards with your own paper and ink, and play dominion with all the expansions that way, and Donald never gets a cent (if you change the wording and art slightly). I don't think that is in the good spirit of things, Donald worked to design that so that he could get paid something when you benefit from the testing he had to do to figure out that your games were all going to degenerate if Jack could trash treasures.
There's illegal things that are in good spirit. If you buy all the cards on Goko, then pay a friend 50$ to photocopy all his Dominion cards for you to play with, that is in good spirit because you paid for #1, but that is actually illegal.
You should have to pay for #1. But you shouldn't have to pay for #1 twice.
Buying the physical board games and making your own dominion server isn't allowed, though. It is illegal, but in good spirit, because each player pays for #1 at least once.
The laws don't stand in the favor of the way I think things should work, but capitalism has this really neat feature where you can vote with your dollar, so that's what I'm doing.
By the way, the guy arguing that a free version of dominion wouldn't happen if it was legal, I don't think you are right. Personman was willing to donate a thousand dollars or something to keep isotropic up. There's plenty of interest in the game and, hey, one person has already implemented it before free before, I really think a small group could probably do it too.
The main reason it won't be happening is because it would get shut down for illegality.