The point of the new list is not so people do not apply demand, it's for people to apply demand at their discretion. The old list already incorporated demand and even then people would re-aply demand. I really think it will help bring certain pet prices down as people are only trading certain pets for crazy amounts because they think they're rare on top of having high demand as well as what was previously explained (x person paid y amount so I want a little more out of it).
As for store pets staying rare for a while, I'm pretty sure two of the store corgis were rare up until this year or last