These points are presented in no order.
Based on the thread in the rares forum, it wasn't intentional. There was an official reward from the event, a candle, and I've yet to attend an EM event that had 2 rewards. The far more common complaint is having none.
Origin was created in 2004, Phoenix Armor was available in 1999. In other words, the only way people on Origin had access to this item was by someone transferring on it.
It's far from without precedent for a hitherto-rare item to become less rare, or not rare at all. Daemon Bone for one, once rare then a common drop from Doom Monsters, and part of the Gauntlet Quest. Once upon a time, Bone Armor wasn't craftable: It was a semi-rare drop from monsters and it provided good protection without a dex penalty. More-recently, but still some years back, we had one of those rare "unintended but legal" things involving those items you get off the ground that are supposed to be locked down but aren't.
How many times have I read complaints about items being too rare? How many times have I read complaints about items not being rare enough? How many times have I read complaints about rares collectors all being dupers and scammers (which I, for one, do not believe)?
Damned, in all variations.
*shrugs*
-Galen's player