Often I hear about how dungeons are more "expensive" than other contents such as scenarios or dailies to make.
I don't really understand why - other contents take a lot to make.
For example, the thunder isle is a completely new zone, with gozilions of different quest mobs, and chains of quests, plus gradual unlocking of the isle and etc. Heroic scenarios too require new zones and tuning too.
Is there any reason why dungeons are especially costly?