I agree that if your goal is to be centralized, heavily control what your users see, and only your team is capable of doing such a thing, then federation is not the solution.
However, as someone on the outside looking in, I doubt you would have the user base you do, or maintain it for very long if it were just an old-style centralized forum. It seems to me that those forums were simply not preferable to the level of content and connectivity offered by the myspaces, facebooks, diggs, and reddits of the world.
If you're open to maintain interaction with other servers, and just find moderation too resource intensive, then I think you're probably just bigger than you can afford right now, and should shoot for fewer DAUs.
The number of people out there who want a safe space for the disenfranchised can't just be your moderation team, and that's why the fediverse exists. Amortize that responsibility over multiple instances, don't feel like it's something that only you are able to solve.