A new world pvp zone in which you can collect sub arena quality gear if you do the linked PVE and one new battleground to collect the same items you already have the capped number of
or prolly like 10 new 5 mans with heroic modes and a whole set of raids to collect a different item that serves the same purpose as the one you have lots of now
in terms of content these situations aren't really comparable, especially since pvpers will still need to do the old content (ab, wsg, dear god not eots and av pleeease) if they want their new equipment. I don't imagine raiders will still have to do UBRS for tier 7.
You forgot the part where Wintergrasp awards about 5k Honor to the winners and about 500 Arena Points (Subject to change). Not countng the several daily quests located there, as well as about 7 additional PvP centric Dailies in Grizzly Hills.
So no, You're not forced to participate in the old BGs again, Honor and Arena points are easier to get then ever.
Oh and for the record Raiders are doing Naxx again for T7