OMG yes to more frigging locks for worksets and categories.
It would be pretty easy programmatically too - just add another column in Visibility Graphics under each tab that permits changing editability (e.g, Default, Always Editable, Never Editable). Since hydronic piping is a kludge for sizing Storm piping, gas piping and refrigerant piping, workset locks are needed as well as category locks. It is necessary to coordinate with other disciplines, so turning worksets off (VG) is not so good for coordinating.
Coming from AutoCad, this lack is one of the stupidest things in Revit. Clicking EDITABLE ONLY works for about 30 seconds (till I do one of the 17 things that turn that back off without telling me). If AutoDesk is not quite sure, I suggest they remove the ability to lock layers in AutoCad and see how the user response goes....