At this point I think the only way to make pvp popular for NA/EU is to add very substantial, unique non-pvp rewards, like how deep dungeon got IL 235 weapons which are easy to get. The really hardcore pvp players hate ideas like that because they don't want matches diluted with low-skill casual players, but it seems like that is already the case right now with people complaining about being matched with unranked players.

The matchmaking works like that because more fair matches are not available, it's just using whoever is available after failing to find a more even match. If reward incentives increased the pvp population, you'd see more people learning and a fraction of those people getting good and reaching the higher ratings, allowing the matchmaking system more choices to make better matches in those higher tiers.