What if not every choose to transfer, even for free, wouldn't the free transfer now stop those people from enjoying the game?That would mean the original reason for you wanting free transfers, enjoyment, isn't being solved by free transfers. But I'm guessing at that point you wouldn't care any more because you got to transfer for free right?
And if people have been complaining about low or unbalanced populations for years, why is it that you were arguing earlier that it started with Cataclysm and continued with MoP? You do realize that Blizzard created CRZ at the end of Cataclysm, and is connecting realms at the end of MoP. They are doing stuff about it but like I said before it can't be instant.
Would you rather then rush to merge servers and screw something up? How many players would quit if Blizzard screwed up their characters? Or even some random internet persons characters? How many people would panic or fear for their own if another servers got screwed up? But its a good thing that Blizzard has a service since 2006 for those that are tired of waiting for a long list of fixes (FCM, New player recommended servers, Paid transfer discounts, CRZ, Recruit a friend, Scroll of Resurrection) that haven't done enough.
You can either pay to have it your way now, or wait for Connected realms to finish and have a populated server again. Which may or may not actually solve the real issues with your enjoyment of the game. As I doubt having High populations on every server would still have kept people playing the game. After all you made the claim earlier that it was Cataclysm and Mists of Pandaria that made people quit, and not the realm populations themselves.