As usual, your comments are spot-on and well made. They are always a good read. I'm wondering if you are posting this elsewhere as I suspect this forum does not get a lot of reads (though occasionally some designers and developers may reply to something which shows it does get read.).
As a feedback to what you wrote, I suspect if there was any marketing/product management techniques involved in leaving the original content alone. For one, it takes additional resources to revamp these features such as AQ. For two, the players are more likely to buy the new expansion if they realize that it offers better rewards. Noone likes to miss anything good.