just have him file IFR all the time

Given the misinterpretations that even IFR pilots have with ATC's responsibility for weather, this is probably a bad line of thought. I hear plenty of terrain warnings issued with IFR flight, not so many with VFR given the same criteria. I would agree it's foolish NOT to use FF in crowded areas and on VFR XCs, but to think it's "almost as good as" IFR oversight is a stretch, that level of service varies widely in my experience and can create a false sense of security.

Variation on the theme: Also teach them to update the flight plan with position reports. It's a technique that I learned flying in the Rockies where radar coverage for flight following can be spotty.

Consider that the purpose of a VFR flight plan is to give S&R some place to look. If you never show up at your destination, you could have gone down anywhere on that route. With position reports, you're limiting the search area - they don't have to search the portion of the route behind where you last reported.

I don't use it as a false sense of security, I use it as simply another layer of defense in a very crowded environment. I have had to use abrupt maneuvers to avoid a collision three times in SOCAL, twice 91, once 121 (always involving ther GA airplanes)

Agree with other posters. I think it is a good idea to give the student more experience using the radios and FSS. I've run across several students who hardly ever used flight service in their training and did not have a good idea how the system worked. Plus, back when I was doing my private solo cross countries, I felt a bit better knowing "somebody" was watching out for me when I had the flight plan activated.