You'd be surprised at the amount of threads I move... it's definitely a lot more than the complaining I do. If I see a thread that shouldn't be where it is, I move it. Unfortunately I can't spend 24/7 scanning every forum, and neither can the mod team. That's why we give you options to pm a mod or post in the various threads. We're generally pretty good at responding and helping you out with your request.
And yes, a report button could be useful -- but what happens if the report button gets abused and every thread ends up getting flagged for stupid reasons? A lot of features members conceptualize actually take a lot more time (and a lot more challenging) to implement properly than you would assume.