Gaining 3m non-loyal players who got rekt by blizzard's clever marketing isn't exactly losing 3m subs, it's losing 3m players who never really were there. Those locusts are just for the money grab and wouldn't ever stick with wow long term, no matter how "good" it was.
Just like the people unsubbing over non-flying. Those aren't loyal wow players either. It's expected people like those come and go as time passes