lets be fair on the 3 trees thing... yes technically there are three trees but lets face it being locked out of nature totally gimps Elemental specs DPS.
Every 5 secs (if talented) either ~900 damage and DoT or ~1500 damage and 3K aggro, and a mana inefficient as you like... I remember doing a quest in Nagrand where you had to kill elementals who were immune to Nature... I ended up beating them down with my axe. it was horrible.