Moonfire and Starfall are arcane just for game mechanics, just like how a hunter using arcane shot doesn't mean he can use magic.

@Xino

Ehhhh, plausible but we're not talking about game mechanics here. We're talking about lore, and in the world of Azeroth different schools of magic have their individual sources.

For the sake of game mechanics it could just as easily be nature magic since it's called /moon/fire and /star/fall. Granted it might simply be an oversight on the part of Blizzard, but in the context of lore using arcane magic is still using arcane magic. A hunter may be using an arrowhead crafted from something charged with arcane energy (a structure fragment from the Well of Eternity exploding?), but a druid /casts/ Moonfire and Starfall. They're drawing on the arcane school of magic /instead/ of nature. I see a high elf vs. night elf dance off in the near future!

http://www.wow.com/2008/12/04/know-your-lore-dalaran

Its pure gameplay mechanic so druids still have something to do when Counterspelled or otherwise interrupted. They'd be completely locked out except for shapeshifting/staff melee (lol). Shamans have the same problem. The whole "star" or "moon" thing is just an excuse for the arcane spells.

@Cedarr

That's not necessarily true either or Paladins would have a similar fallback. Paladins also shun arcane magic, but since Holy is their only school Counterspell or similar attacks will lock them out for as long as the effect lasts. Again it looks like night elf druids draw from two schools of magic: nature and a little arcane when they're in a fix. Or need one. :) Again the Shen'dralar probably have a few bones to pick with Fandral Staghelm, or the maybe the sindorei should give a talk about denial and addiction?