Another Poll should be made. I'm sure the results would be proportional to the number of people that (actually) use the 'Threaded' mode. Such as...
Do you open links in
a) New Tabs (flat users)
b) New Windows (threaded users)
When hammering nails I like to
a) Smash my fingers (threaded users)
b) Just get the job done (flat users)
When posting links I go out of my way to
a) make it a link that reroutes the page you're currently on - 'cause I'm a dick. (threaded users)
b) be considerate and just post the url as the link so it opens in a new window or tab (flat users) ...which really doesn't take that much effort. The forum software takes care of that.