That also impacts Hearthstone and Diablo III's auction house, which shuts down March 18th. The setting can easily be reversed to see bank balances plummet for new pets.
"We're making this change to ensure that Parental Controls users will have more control over real-money purchases in Blizzard games," explained Blizzard.
Hearthstone is Blizzard's new card-battling spin-off for World of Warcraft and likely to entice some of the younger generations who've no concept of a 'DOS command' or that micro-transactions are evil, and so necessary barriers are needed to help shield older generations who can't grasp the concept of iTunes synching to hear music.
Maybe some adults would like to prevent themselves from in-app purchases? Grand-Parental Controls maybe?