It's nowhere near the same as buying gold. There is no new gold being generated, the gold is just trading hands. If they "sold gold," gold would be generated, and flood the market. This is not the case.
As far as it being BoE goes, people were selling pets regardless of the BoP tag, and a lot of people were getting scammed. And as far as combating gold sellers, they are. The gold sellers (or anybody for that matter), now, cannot sell that pet and go cancel their credit card, running off with your gold and leaving you with no pet.
So, with your logic, people selling trading card game mounts (bought IRL with real money, sold in-game for hundreds of thousands of gold), which are in fact also BoE, is Blizzard "selling gold" too, no?
Oh wait, it's not.
And no, TCG items absolutely do NOT need to be BoA. You'd be significantly taking away the rarity and value.
Edit: As far as store items go, they should be account-wide.. once learned. The pet should be BoE, as it is now, able to be sold, but once learned, should send BoP versions of it to all of your toons and any in the future. That would make it act like all of the other store items, yet not allow people to sell multiples from one purchase.
Edited by Anachronism on 11/3/2011 3:49 PM PDT