Which is exactly what EA is doing but with OPTIONAL content.
Perceived value of anything you buy is based on what you can get when you sell it. So if I buy a game for $59.99 I am already thinking I can sell it for $49.99 later so it is only costing me $10.00. If I can not sell it for $49.99 later since for anyone to go online they need to pay an additional $20) the value of the game (sold as used) goes down further and further and the amount I perceive as paying for that content goes up.