Cons: there are lots of "features" which are not listed there, and also there are going to be settings that are not in the same place as the "big switch" to turn that thing on and off

But overall I think +1 ... perhaps we need some more votes though.

Anyway, some comments after chatting with Petr a bit (perhaps for next revision):

• Perhaps it could be possible to have one more item under "Admin->Modules" (like activities, blocks and filters). Call it "subsystems" (or whatever you decide).
• That item will work exactly like the others, with one main "Manage subsystems" page, used as general switcher and then, one specialised settings page for each subsystem.

IMO, that would be more "in sync" with other modules providing a better (consistent) user experience.

Also, could be interesting to "normalise" subsystem switcher names, instead of everyone having its own custom name, something like "subsystem_blog, subsystem_tags, subsystem_messaging..." or so.

Just some ideas FYC.

My +1 remains for current Petr proposal, anyway. Ciao