To me, the "boring years" are when the ripples settle down. The dust clears and everyone adjusts to the changes made. New Vegas' world is not still feeling the immediate impact of the war with the Enclave, nor was Fallout 2's world still feeling the immediate impact of the Master's plan. I don't think setting Fallout 4 right on the heels of Fallout 3's story is the same thing, as the ripples are still rippling.
I just mean that it'll be placing too much importance on Fallout 3's events if we're still tying them up in Fallout 4. If we're picking up with the Enclave and Super Mutants still being picked off by the Brotherhood with no cessation of hostilities, that would kind of mean Fallout 3 lacks a real resolution. One of my big problems with Broken Steel was how it treated the ending of the game. The whole thing with Project Purity, which was obviously the center piece of the narrative? Turns out that's not the real ending, because we still have to fight the Enclave more! If this is a direct continuation of the hostilities, that would basically be going "Guess what!? Destroying the Mobile Base didn't finish the narrative either, because we're still going on with this fight that has clearly been wrapped up twice already!"
The story of the Brotherhood's conflicts with the Super Mutants of DC and the Enclave should be over. That fight should be over. They can be reignited, as conflicts often are, but I don't think we should be playing what are essentially the dying embers of a fire from 7 years ago. I'd rather have a new fire.
I hope it isn't a direct continuation either. My fear about it being in the same timeframe is that a concurrent story prevents any real meaningful narrative building from the events of Fallout 3. I'm afraid of seeing references being something like "Yeah, things are crazy in DC right now!" rather than say, finding a traveler who talks about what the Capital Wasteland is like now that the fighting is done. With the concurrent stories, Fallout 3's events are either going to have too much impact on Fallout 4, if we are seeing something like the Brotherhood's wars spilling into the Commonwealth, or too little because it's too soon for the effects to have taken shape in DC.