Because some are just better than others.
You know what I'm talkin' about.
Here's my list of my (present) favorites. If your favorite isn't on here, don't worry. I've almost certainly played it, I just like these ones better. But go ahead -- tell me why you like your favorite games. I'm always down for something new to try. We might learn something from each other.
Crazier things have happened.
Betrayal at House on the Hill - One of my all time favorites. I love the mood, the theme, and how each time you play it is inherently unique. From a design standpoint I love mix and match maps that grow as you play with friends. It is such an organic approach to gaming.
Cards Against Humanity - I mean how can this not be one of my favs? Excellent party game as long as you don't play with boring people.
Beasts of Balance - If Jenga had a much cool baby this would be it. The new addition of being able to have battles with friends is going to be epic.
...... and a ton more. I'll update as I feel like it.