That's a pretty lame ass/sucky reason - by that philosophy then they should remove enchants, sharpening stones, armor patches and gems (not that I want them to - just pointing out the failure of their "reasoning").
It's a perfectly valid reason. The issue with the oils was that everyone
could put them on their weapons and still use flasks/elixirs. It's not like their were AP/avoidance oils, and really, the fewer consumables I need to be bringing to raids the better. Enchanters don't need anymore. They never did. They have D/Eing and enchanting all rolled into one. That can sell mats and they can sell enchants. It's good stuff.
Or, to clarify the logic, why not make it so that alchemists can sell herbal gear augments, or JCs can make consumable stat augments ala flasks? Before you know it you end up with one 18 slot bag set aside specifically for food, flasks/elixirs, potions, enchanting oils and JC consumables, and when you next upgrade a piece of gear not only do you get to fork over for the enchant/belt buckle and gems, now you get to cough up the gold/mats for your alchemy augment.
Sometimes less is more.