While I'm more tech savvy than most people I know, a lot of my friends have uninstalled the Facebook app as well, for a variety of similar reasons. Several have noticed what a battery hog it is, others got pissed off when Facebook added the messenger app, and others did it for privacy reasons.
Interestingly, I've noticed I use Facebook a lot less since deleting the app. I should see how my friends usage trends compare. I wonder if the friends who deleted the app have noticed a decrease in their Facebook usage, or if all my friends have decreased their usage and it's just a function of us being older/in different stages of life.