Well, the rating only exists so that you might find players of equal skill. Playing someone of equal skill is fun if you can sometimes still learn something or have a real nail biter where small details matter a lot.
But with Dominion, there's so much randomness that when you're playing someone of comparable skill the game is most likely decided on shuffle luck instead of keen tactics. If you play a chess match against someone rated 100 points below you on the ELO system, say you're 1700 playing a 1600, you could win close to 100% of the games, simply because you know everything the 1600 knows and a bit more.
The rating system on Goko uses 4 significant digits and a ladder, corrupting the system in my view. If you create a ladder, you're making players play just for their rating instead of the fun the game offers. I think it's wrong that people should be worried about dropping any levels on a ladder over such a simple game. A ladder makes people scared of losing and stops innovation.
What I would have liked to see is just one significant digit or even one half and no ladder. Rate the players 1-5 stars or something. This way you can use the rating the way it was intended: To find players of similar skill.