I probably still have a copy of the original Guildwars and played it a lot, all single player. IIRC there was multiplayer but it was optional, not mandatory and the game played more like a traditional RPG. I never got back into it despite there being a sequel but it definitely wasn't the worst. I think that's the way to do this stuff - make people buy the game and design the game to be enjoyed. If monetization is needed then sell cosmetics, clan stuff etc. which don't impact on the game.

Around the same period of time I also tried games like Dark Age of Camelot, City of Heroes, City of Villains, A Tale in the Desert (a weird indy MMO), Lord of the Rings Online and a bunch of others. I even played World of Warcraft in beta, and a few times for short stints but always the same grind.