Actually Django and Bootstrap are my bread and butter too!
I stick to them for anything mildly serious.
It Just Works™ and the Django group is not trying to steer Django into something that it's not. Same with Flask.
I like using flask but django always felt half baked to me vs rails.
Yes, it's totally worth learning in 2020.
Maybe someday I will use Django more, once I'm deeper into Python or perhaps I can find a freelance Django project.