I think that it's clearly a win on almost all fronts. The only people who would be objecting is the people who were previously raking in the cash from monopolising the market, and even then their motivation is just greed - so that's not going to be a really valid opposition to this change.
My server is 1.4:1 Alliance:Horde. So I'm wondering what impact that will have on our AH - not that I am a big AH player mind you - but for those realms where the population skew is MASSIVE (eg Dath'remar 2.4:1 or Blackrock 1:10.5) then it will be so amazing for the lower population faction to now have access to cheaper goods!
However, if you think of the RP aspects of the game do I really want to be buying stuff from my faction's enemy? In reality, most of us don't really treat the alliance as enemies - we have toons on both sides! But I do hope they include which faction the item being sold is from as I would PREFER to buy from Horde, but you know how market competition is, we will buy the cheapest! And I think of all those rare spawn things that I can now find ...
When I brought it up in guild there was a lot of opposition.
"It will ruin our server economy!"
"There will be a crash in profession gold making."
"How are we going to make money now?"
"It's a stupid idea."
It sounded to me like opposing Free Trade. Domestic markets unwilling to open up because of the fear that they will harm their current economy or monopoly. What if the competition is using less than ethical techniques - such as ... umm... slave labour to gather those herbs? Or duping mounts/pets? Those cheaters ruin it for everyone as the genuine crafters/sellers will be unable to compete with their prices. And what about the consideration of BUYING from the enemy? It's like selling arms to a country that's going to attack you with the weapons that you sold them! I suppose that's really just an RP aspect of this game, but I hope that they somehow put some kind of annotation on live so you know whether you're purchasing from Alliance or Horde. Maybe they could have a little "extra" tax for doing it cross faction as a slight deterrence and to protect the Horde economy a little!