AotV reduces our damage by MORE THAN 50%. Part of winning arenas is about forcing another team defensive and forcing their healers to ... heal. The most dangerous thing you can encounter in many situations is a healer that is able to assist in his teams offensive pressure/control.
There is no exaggerating the FACT that you will be losing 18% dodge, 30% run speed on dodge, and 300+ attack power EVERY time you want to get some mana back.
Working on regen between kill pushes is something easily done when you're not being focused but when you are the target the other team is trying to sit down switching to aotv can be a very painful experience.
Didn't you just link a build with Aspect Mastery in it? And 355 attack power isn't going to be as substantial a part of your dps when you're fully kitted out in s5 deadly. Instead of losing "over 50% of your dps" you're losing either 5X% without Aspect Mastery or 4X% with it (and X is a low % that is only going to decrease from season to season.)
Again, you're ignoring the fact that every
class with a mana bar has to be judicious when they're getting low. Mages have to hide and evocate, Druids have to find a pillar and Innervate if you have any kind of offensive dispel, Locks have to watch their taps when they're low on HP, Shaman have to try to hide their mana tide where it won't be one-shot, Priests have to be careful their shadowfiend wont' be PW:S'd or IB'd or Shadow Ward'd or Feared into giving them no regen, they have to create breathing room to channel Hymn of Hope, Pallies have to make sure they don't pop Divine Plea when the other team is putting out a lot of pressure and everyone has to run away and do absolutely no damage or CC in order to drink.
You, by comparison, lose a bit of melee mitigation. At a point in the fight when people's trinkets are probably down and you can probably safely make breathing room with scatter, disengage, etc.
Take a little solace in the fact that, out of all these classes, you can still operate at 50-60% effectiveness in terms of DPS and 100% effectiveness in terms of CC and still are able to use your pet while exercising your means of mana regeneration. Your tradeoff is taking a little longer to get that mana back, but remember that it doesn't take you any cooldowns to do so, unlike every other mana user except locks (and discounting drinking, obviously.)