I can't speak for anyone other than myself but I found Vicky 2 pretty recently, and even then it took me a while to really love the game. My first play through I pretty much sat there and did nothing but it was interesting enough for me to keep at it and learn the systems and figure out what was going on, which I guess is a mark of excellence if something is good enough to make someone with no idea how to play engaged enough to learn.
To borrow from the recent PDXcon talks my real love of Vicky started when I realized just how wall the game was made. How the markets reflect the randomness of real world market fluctuation, how capitalists try to guess what the markets will do when funding projects and sometimes guess wrong, how the armies are broken up into different units that do different things.
But more than that, my love for Vicky is because you can paint the map, but you don't have to. For me it's more fun administering the realm so to speak and Vicky does that excellently. It's why Ck2 is the greatest paradox title and why Imperator is not that good, imo at least. You can pick a secondary power and be more than content managing it into an economic leader. You can follow the optimal tech route or you can not and it won't terribly handicap your run. You can set about westernizing a non western tech group. There's dozens of ways to play and different nations feel different to play. It isn't like EU4 where playing china is like playing France but with some flavor. Playing China in Vick is an entirely different experience than say the UK, your priorities are different, the things you will do are different, what goals you can rationally set are different.
Side note, this tutorial series taught me how to play. It's a time investment but I really do recommend learning how to play, at worse you waste a few hours learing about game design at best you'll learn how to play the best game to ever come out of paradox