Any piece of software that doesn't essentially force an upgrade on you will end up used in a lot of deployments that never upgrade. Not much we can do about that.
Though you're right that people tend to "stick" on a version where the next step up is a trickier upgrade. That's happened a couple times in Django's history -- a lot of early deployments (pre-1.0) pinned for a long time on 0.91 since the Django ORM got completely rewritten for 0.95.
And post-1.0, the switch to class-based generic views also left some people behind. 1.11 is likely to be "sticky" too since it's the last version that will support Python 2 (the next release -- Django 2.0 -- will be Python-3-only, and 1.11's LTS support cycle is timed to expire when upstream support for Python 2.7 does).
Though you're right that people tend to "stick" on a version where the next step up is a trickier upgrade. That's happened a couple times in Django's history -- a lot of early deployments (pre-1.0) pinned for a long time on 0.91 since the Django ORM got completely rewritten for 0.95.
And post-1.0, the switch to class-based generic views also left some people behind. 1.11 is likely to be "sticky" too since it's the last version that will support Python 2 (the next release -- Django 2.0 -- will be Python-3-only, and 1.11's LTS support cycle is timed to expire when upstream support for Python 2.7 does).