I think that some people are forgetting that development costs are much higher than last gen and that publishers generate much less profit.
Now imagine there wouldn't be some guys who buy new costumes, weapons etc.
It's a great way for the companies to generate money without spending too much on developement.
Don't forget, you DON'T have to buy them if you don't like them, but if there were no DLC I could imagine that all publishers would raise the retail price for their games to make up for the money that was lost during the developement.
So either you pay $10 more at launch for EVERY game or you pay the same price and have option of paying some stuff later on.