MyBB Community Forums

Currently, the only privacy option for users, in their user control panel, is:

"Hide me from the Who's Online list."

I would suggest adding a new privacy option there:

"Hide my time spent online"

One example of how this would be useful: in games/entertainment forums (and similars) some people don't want others to know how much free time they have.

And in general, in our "digital stalker" era, this information should be able to be protected by the users.

Thank you.

Personally I don't think this information should be publicly visible at all. It's not useful to anyone.

Nothing on the user's profile is really "useful to anyone".
Post count: Could be trigger happy with useless posts
Joined date: User may not have posted for years and still be a newbie
Time spent online: Could use a bot/refreshing script
etc.
(In fact, the only real useful thing to me is the user's local time and last visit I suppose. )

But a combination of these things may give you a better insight.

I've always sort of though that the "Hide me from the Who's Online list" should automatically remove the "Last Visit" bit on the profile.

All sort of nit-picky things though... :p

If the forum niche does not require this it can be removed by editing the templates.

No need, I find. As Tom said, you could opt for it if you wish to.