I've been working on the quest for epic flight form for my Alliance druid recently. I know I could just train it, but doing it the "proper" way just feels more rewarding to me, not to mention that it's simply an extremely cool and entertaining quest line. I now have Vanquish the Raven God in my quest log, and figured that with the dungeon finder it should be easy enough to get a group for it these days. Oh how wrong I was.
I don't know how much time I've spent sitting in the queue and waiting for a group for heroic Sethekk Halls in total by now, but it must add up to several hours. At no point did I ever see more than two other icons light up as the group was being assembled, even though I had signed up as able to fulfill all three roles to be as accomodating as possible. Often I'm utterly alone. It's discouraging.
I can understand that BC heroics are nowhere near as popular as the normal Northrend dungeons - there's no emblem reward and most drops are outclassed by Northrend greens. But still, I would have thought that there would still be some interest, be it for the achievements or simply a change of pace. I'm sure many altholics are tired of running normal Nexus for the umpteenth time, and I would have thought that simple curiosity would be enough to lure the occasional newbie into a BC heroic as well. After all I had little trouble getting into the old level seventy instances on normal mode, and that's with Blizzard removing the "random Outland dungeon" option from the dungeon finder at level sixty-nine or so, so you can only get into instances like Magister's Terrace if you sign up for them specifically. At least "random Outland heroic" remains an option for several levels. Why is that not enough?
My best guess at the moment is that the old attunements are simply too much of a stumbling block. I like attunements in general, but keeping them in place for instances that are nothing but levelling dungeons these days strikes me as a mistake on Blizzard's part. I know they are not at all difficult, and people might even reach the honoured requirement with various factions without as much as trying, but actually buying the keys requires knowledge that many curious newbies probably don't have, and effort that the jaded veterans might not want to bother with, as in: they might consider queuing up for an old heroic on a whim, but once they realise that they are locked out because they didn't think of buying all the keys while they were levelling through Outland, what are the chances that they'll actually stop their questing in Howling Fjord to march all the way back to Zangarmarsh or wherever just to buy those keys? Not very high, that's what.
The old Caverns of Time instances have the same problem, even on normal mode, seeing how you can't enter them without completing this quest first, which is a massive shame considering how much fun Escape from Durnholde and Opening of the Dark Portal are to play through. But again, a new player simply receives no pointers that this attunement is needed at all, and a veteran might simply not want to bother with flying down to Tanaris and then trudging in a circle for ten minutes just to unlock another instance that he'll soon outlevel anyway.
I did get lucky with Old Hillsbrad myself as I got a group almost instantly, but it was telling that one of the dps immediately exclaimed: "Finally, we've been in the queue for this one for three hours!" And the only reason that I got the Black Morass completed as well that day was that the group from Durnholde wanted to continue straight towards the followup really badly, probably knowing full well that they might not get another chance at finding a high enough number of attuned people anytime soon.
Really, it is just bizarre that it requires more effort to get into an Outland heroic than to get into a Northrend one, even though the former is levelling content that provides very little reward. I'm all for making people work to reach the top of the game, but if you want people to group while levelling as well, you really mustn't throw hurdles like that in their way (or even leave them as forgotten leftovers from a different time).