This game isn't W0W and this change will have a VERY minimal impact on people leaving WZ's.
How can you say this will have a very minimal impact on people leaving warzones. If there are so many ppl that want to queue for both, it will have far more than a minimal impact. I doubt too many of the ppl will wanna be rude enough to tell their party members, "Oh, could you please wait like 12 minutes while I finish a warzone?".