Playing an online game is a crazy luxury. You are spending both time AND money on something completely non productive. If you have the 12-15 dollars a month to pay for a subscription, it's hard to imagine someone who can't cough up 2 dollars per month for something else. If I had to worry about 2 dollars a month, the last thing I would be doing is playing video games.
I've gone for a long time with 2 free retainers. I only made the decision to grab the other 2 recently because it became more trouble than it was worth to parse down my crafting mats into expensive/rare only.
I'm not saying you HAVE to pay, just that the pricing for extra services in this game aren't unreasonable.
and before I get the "RENTING SPACE" argument: you are renting space already by subscribing, agreeing to rent MORE space isn't a sin.