FF, I don't think the issue is so much about if people have a degree or not, it is rather about people claiming to have a degree when they don't, which is dishonesty.
If you are employed on the grounds of having a degree, then a degree you should have.
I know plenty of teachers without degrees, and they are very good at their job, and just as importantly they didn't gain their employment through deception.
I quite agree that a degree in film studies does not automatically qualify you as a teacher, but what it does do is show that you have been able to attain a certain level of education, a level of education that you can then encourage your students to either match or surpass.
For me, the problem with people using fake degrees boils down to the fact that they are bullshitting their employer and their students, if you ain’t got a degree, fine, but rather than making a fake one why not try highlighting on your CV why you are a great teacher – shit loads of experience, a people person, patient and understanding, good organizer etc. etc.