I've been using Revit since version 8. We have used BIM exclusively as a firm since 2007, I don't need any lectures about sharing and collaborating in Revit. I'm a huge proponent of Collaboration for Revit, it's been a tremendously useful tool. And we all have access to everyone's model on the team at any given moment. No one gripes about their "IP". In the beginnings, I thought how you do. But now it just seems passe.
Tesla, Google, Microsoft etc all embrace open source software and property in many respects. They aren't worried about anyone stealing their stuff, they just want to advance the technology.
1) It sounds like your team members need to be versed in how to use Revit appropriately. Locking it down for them doesn't do them any good. Heck, if they knew more about the parameters and functionality, they might even be able to help promote even greater efficiency. You never know who will have a great idea. But you need to give them the chance.
2) Maybe I trust people too much, I sincerely doubt there are people out there that work on a project team just trying to score Revit stuff. I can't imagine anyone is thinking "yes! we just saved 100 hours by stealing this template!" If they are, something tells me they won't be that successful as a firm. A lot of clients do demand the final BIM model, it's their property, not yours. You were hired to create it for them for facility management etc. Heck, we've been hired sometimes to only create an open BIM model for Universities etc use. You can't lock that down, it's now theirs.
3) Imagine working on a hospital addition 10 years from now, the owner has the existing model for you. But unfortunately you can't use much of it because there is password protection all over the place.
4) I'm pretty sure the PDF standard has protection primarily for contract related items. Not to prevent people from stealing a wall section