I did the same purging of random Facebook 'acquaintances' when I graduated (2009). Then even a year later I was able to trim that 140-150 down to about 80. I also deleted all the random people I had lost touch with from high school who were no longer relevant to me, as since they were added we hadn't bothered to communicate.
I realized a lot of people on Facebook are there to collect friends like it's a status symbol. I really didn't like having college friends, coworkers, professors, high school buddies, employers, random celebrities/bands all lumped into one list together, there needs to be a way too separate these groups.
I was on Facebook when there were only a few schools on it, and it was very useful and very relevant. Because there were no other schools on it, I was only friends with friends from college and there were certainly no high schoolers or parents on it; you had to have a university address.
Facebook essentially got to where they were because that privacy made it awesome, and then promptly lost the very thing that made people trust them with their data to begin with, which was a limited user base.
I realized a lot of people on Facebook are there to collect friends like it's a status symbol. I really didn't like having college friends, coworkers, professors, high school buddies, employers, random celebrities/bands all lumped into one list together, there needs to be a way too separate these groups.