Legally speaking Goko was also a subscription right? You were subscribed to use Seaside for say, a day, then added onto that, however long Goko chose to give you with it using their right to terminate your account whenever. (I'm kinda making up a day but if you bought Seaside and only got to use it for fourteen hours and didn't get your money back I feel like a small claims court judge would give you your money back probably).
When you buy a subscription based on trust like that you should kinda decide how much you trust the company, how much you believe in it, and whether it's worth the risk, and etc. That's kind of what you have to do. When you buy Spotify you know they're a big fish so there's some trust there. Spotify could totally terminate your service on the basis of "one of your favorite artists asked for higher royalties and it's stressing us out", I bet seven nickels their ToS is written liberally enough to allow it, and then they could save some money, but you know they won't do that because reputation etc, and if they did I bet you would switch to Apple Music.
It's up to you to as a consumer to decide what level of transparency you expect from MF about the license expiration possibility, and how much compensation you think you deserve for losing the service. MF has other products, so it's totally within their power to offer you an equal amount of financial credit matching your Dominion purchase on their other products, but they have chosen not to, as far as I know. They could also give you some sort of refund. But it sounds like you want to forgive MF more than that, that's fine. But they knew the license might expire, and the revocation they are doing is analagous to the Spotify example.
There was no trust going on with Rio Grande Games when you bought the MF Dominion though. I don't really see it. There's no agreement with them. I actually have a lot of sympathy for the notion that buying the physical board game and RGG also being able to sell and restrict an online license is double dipping, and most of the forum thinks I'm crazy for that, but blaming RGG for when MF stops extending your 1 day of seaside as generously as you'd hoped, I don't get it.