As a player in BC, I think it was a different experience. BC was about who you knew on your realm and what guild you were in. Good tanks still didn't pug server groups (from my experience). Good tanks ran with their guild. Our MT for raids did the daily heroic, or ran A heroic as necessary to get people keys for Kara, crafting mats, whatever. Back in BC, I don't really remember going into Heroics once I was raiding. I'd help key people for Kara, or to the Champion of The Naaru title pre-raid stuff. But otherwise, I'd be crafting for guildies or something. Our tanks were the same way. They'd run someone if they needed something, but otherwise, we signed on to raid and that was that. At that point, we had so many badges we didn't know what to do with them. 4-hour drunk off our butts Kara and ZA were more interesting alternatives for us than a Heroic.

People without raiding guilds in BC probably did PuG. I just wasn't aware of it happening. Most of my friends who didn't raid didn't usually PuG. They just sat with their gear or did PvP.

I guess in some ways, it hasn't changed a lot then from BC to Cata (in my eyes).