I doubt Blizzard would keep features in check just to be able to score brownie points on them later. In that case I would rather think they were planning on doing the new customization options and such later, but fasttracked it instead.
Mage Tower would require far too much work. Not just the actual challenge itself, but you need to find a good framework for it, and good rewards. Not to mention that the Mage Tower was fairly tightly designed, that isnt just something you whip up over a quick zoom meeting.