I've been playing the multiplayer and Horde mode in the new Gears of War and I constantly see people using premium character skins that each cost 20 bucks (or your local equivalent) a pop. 20€ is what I'd be willing to pay for a whole DLC, or alternatively that's like several days' worth of groceries.
I'd rather games have cosmetic microtransactions instead of paying for DLC or in game currencies. Game developers have to make money somehow. If a bunch of other people buy cosmetics, maybe the developers release DLC for free.
There is a concept called a 'loss leader'. Grocery stores will sell certain products at a loss because it brings more customers in and then those customers buy other things. Game console companies used to sell consoles at a loss or low margin because they would make it back on licensing fees for game sales.
If the developers offer expansion content and/or free online-multiplayer gameplay, there is a loss of income. However, when people are playing the game more, they're more likely to purchase cosmetics. Then the developers make more money than lost.