Do you feel Nexon exploits it's playerbase?

While not entirely apt, the best comparison I can think of is entrapment.
Nexon doesn't "just provide the means", but they also create the incentive.

Entrapment could very easily be pinned on many many many aspects of business, or even life in general. Creating the incentive is indeed part of what they do, but they aren't at all to blame, because that's what we call marketing. Not to say the players individually can do anything about what they decide to do, but they keep the cycle going even if they don't agree with it because they want the benefits despite having the willpower to back away. Nexon's profits prove that.