I think it was good that the requirement to buy heroic keys started at revered, but I think the time has come to reduce it to honored. The population on Medivh is struggling and I think this would help alleviate that. This change originally occurred during the ZA patch. http://eu.battle.net/wow/en/game/patch-notes/2-3-0 I don't think it's a huge deal to make the change early given the circumstances.
Any time a new person reaches 70 in a raiding guild, the guild has to grind 4 different factions just to get one person part of an attunement. Needing revered to enter heroic dungeons is the second biggest barrier to entry to get new players into TK raiding (the first being leveling from 1-70).
Or at least consider making this change whenever BT is implemented.
Yes, it's certainly not the easiest, especially with the population being so low. There are barely any dungeons being run @ 70, which makes it very difficult to attune people