The question about "what is most overrated" I believe is close to the question I ask in the subject header. So, rather than post yet another "overrated" thread question, let me tweak this a bit. I am sure there are certain games and game franchises, which are popular, that you can't figure out why. You wonder how a game that is so derivative, poorly done, or just apparently so boring to you, interests a large number of people.
So, which popular games and franchises are you perplexed as to why they are popular.
Myself, I would go with likely Grand Theft Auto and also Metal Gear Solid. I am more stumped by GTA than I am Metal Gear Solid. WIth Metal Gear, it is more of how anyone can say "Best EVA!" more than anything else. As for Grand Theft Auto, I know the appeal of a sand box, but I don't get the appeal as to why anyone wants to be a psycho criminal and mow down innocent citizens. It just isn't my thing, and I wonder what it is about human nature that drives people to want to do this.
I likely have others, but they slip my mind now.