MMOs are definitely designed to prolong the playing process by way of grinds, time-gating, long time sinks, sunk cost fallacies, and so on.
F2P games are designed to get you to spend in similar ways - not exactly, but similar.
Personally, I do like that F2P games basically let me set my own price but I also dislike how nagging they can feel. On the other hand, WoW doesn't directly nag me all the time - but then it doesn't have to because they're just reaching in and taking the money anyway.