Yes you're right, the thing that happened years ago on a different game with a different developer at a time when multiple Halo games were coming out at the same time is totally relevant now.
Years ago? Try 2011. You know, when Anniversary came out. And by the same developer that's making Halo 4, under the same publisher, the publisher that determined the DLC release schedule for both 3 and Reach.
I got over it by electing to not purchase 4's DLC until after it's all out and on a holiday sale. I bought Halo 3's DLC day 1 because I wanted them to keep it coming. Then we had to wait for two separate game releases just to get the last DLC. Figuring that MS wouldn't do it again, I bought Reach's DLC day 1 (again) because I wanted to say "Hey! Steady content! I like this, give us more!". And then we had to wait until another Halo game came out to get the final pack 9 months after Defiant, while other FPSes got steady content, and you barely get to play the content you bought. It's not a matter of how long the maps had to wait after they were done, it was the fact that you already bought the damn game the maps were for, but had to wait for another game to release before you could buy them.
If Halo 4's third DLC pack (because we already know it has at least 3 packs coming) actually comes out in a normal timescale and not schedule-locked to another game, I'm going to be impressed. Until then, nobody should be in a rush to buy it, as the final Halo 3 content, all of Reach's content, and all of Halo Wars' content showed, MS is not going to drop the price any time soon anyway.
You can map when Halo had good DLC scheduling to bad scheduling from the point Peter Moore left and Don Mattrick was hired.