They originally kept Dire Maul from being implemented at launch because they thought it would impact MC. Given that MC turned out to be an absolute joke, there was no reason not to add Dire Maul early.
They had to add BGs because the world was legitimately unplayable on the majority of PvP servers without them and it absolutely decimated many servers with population imbalances. So, not really surprising that they made the decision to move things up.