There was a period a few years ago when it seems that I friended or was friended-by everyone I was friends with or socially on neutral terms with (I refused to connect with the few ass hats I never liked from those years). I can pretty much find out whatever I want at any time and if I felt compelled to make an impromtu reunion, I could (and "we" have, speaking from the network of people). When the official reunion came up asking for over $100/person, I had a hard time justifying it.
Sure, people went and now I actually regret somewhat not going since there is something to be said about having a proper organized place for all these people to get together. And for the folks who say that "why would I ever want to see XXXX?" The most common thing I heard from a range of friends was that they had a blast hanging out with people that they weren't friends with or never talked to in their life.
I'll definitely go to the next one.