Haven't seen this in the other comments: Coolness factor. If you're a successfully popular teacher, i.e. "cool", then your students will likely want to participate in whatever it is you suggest.
However, if they don't see you as cool, you might have difficulty, and might even put them off the platform. This is not something that can be fixed easily, and trying to be cool is about as uncool as you can get.
(Making it mandatory will work, of course, but how you go about that could determine whether they choose to stay on the platform once you're done. This was kind of covered by OP talking about Matrix in another comment here.)