Druid root is very good for crowd control outdoors due to it working on any mob type, but most instances and raid zones are indoor only. In Burning Crusade the Druid class got a new spell, Cyclone, that worked indoors as well, but with a 6 sec duration (and diminishing returns), it was only effective in limited situations.
Druids have asked loud and long for more reliable crowd control abilities. And now it looks like they might get it.
Player Wisperella recently specced Moonkin and feels she would be more desirable in groups if the Druid Entangling Roots spell were usable indoors. With a 27 second duration and a 1.5 second cast time that can already be made uninterruptible through Talents, it could make Moonkin an integral part of many groups. Especially since Moonkin with their high armor won't get squished so easily trying to crowd control a mob that's pounding on them.
Community Manager Eyonix responded that an idea along these lines is "possible" in the Wrath of the Lich King expansion. He couldn't guarantee that it would happen, but let us know that he has been campaigning for it "a very long time."
Time will tell if this will be one of the handful of new abilities Druids will get in the expansion.