There's quite a few members in my guild that have expressed a desire to run some of the old world content. A lot of them didn't have 60's back in the day, and some of them (like myself) just didn't get in to a raiding guild back then or for whatever reason didn't see the things. So, there's been a lot of talk about it, and even some people going off and actually doing it.
As for me, I'm kinda torn. Yeah, it would be neat to see some of that stuff, but a lot of it is also such a push over for level 70's, that's it's really not a challenge. Furthermore, there's not really anything it for me, per se. Just some fun times, right?
There's a number of old world raids that I haven't completed. Heck, I've never even set foot in BWL or Naxx. Last night, however, after our raid, a guildie asked if I wanted to do AQ40. I got summoned just after an attempt at the Twin Emperors. They said they had worked for a couple nights on it, but the fight just looked trivial. There was 20 of us that easily took down the Emperors. After that, I was kind of bored. We pulled some of the trash mobs after that. Bug mounts dropped like crazy. I even got a cool yellow one. It's a shame that you can only use them in AQ though. Oh well.
I guess some of these old world instances are basically like a few of the 5-mans. Yeah, I could go in and solo Mauradon, but why? I've never completed Wailing Caverns, Ragefire Chasm, Razorfen Downs, or Razorfen Kraul, but I don't feel that I really have to. I find it more of a challenge for the 25-man content we're in now.
I guess that's the beauty of this game though. Everyone plays it differently, so it appeals to many different people and play styles. But hey... at least I got a cool bug mount. :)