Monthly subscriptions are annoying. They cost a certain amount of money that sounds reasonable, but when you add all the months you paid, the amount of money you gave is ridiculous.
15$ x 12 months = 180 dollars a year.
180 dollars a year x 10 000 000 players =
1 BILLION 800 MILLION DOLLARS
There is NO WAY servers and new content could cost that much, or even close, which means Blizzard is making INSANE amount of profits.
Yes, servers cost money to keep running, and new content also costs a lot, but this is ridiculous.
Blizzard needs money to keep WoW working, so a fee is reasonable. But not a monthly fee. A yearly subscription of 50$ or so (like XboX Live Gold) would be more reasonable.
In any case, I don't care, I just got to join a free server. So screw you, all the idiots who paid.