Eloren over on WoW LJ wonders if Blizzard didn't go far enough when they reduced the required reputation for Heroics to Honored level. Personally, even though I'm much closer to the casual end of the spectrum, I never had a problem with Revered reputation -- with my normal questing to 70 and a few instance runs in each zone, I didn't really have a problem grabbing most of the Heroic reputation keys. But even with Honored, some people with different playstyles (solo players, for example, since lots of reputation comes from running instances) are still having trouble.
The good news is that Eloren is basically going to get her wish -- as we talked about last week on the podcast, Blizzard is planning to mix up the ways you can get attuned to a Heroic instance. Heroic Countenance is the first example -- to get attuned to Heroic Magisters', all you've got to do is run the regular once.
In fact, I would be surprised if they didn't play around a little bit with attunements -- for one instance, they might require reputation, for another, turn-in tokens, and for another, a good old-fashioned quest chain. Most of the attunements in Burning Crusade were based specifically on reputation, but there's no reason that has to be the same way in Wrath of the Lich King -- why not give players lots of different ways to reach the different Heroics in the endgame?