As in Fallout 3 GFWL was completely optional. It proved to be a great way to bring PC gaming to the next level with a Service that encompases XBOX 360, Windows Gaming and Soon Mobile.
What the _____ kind of astroturfing is this supposed to be? Which marketing firm do you work for? Exactly how did GFWL bring FO3 "to the next level"? A dozen achievements that were mostly given for following the normal arc of the main quest constitutes the "next level"? Can anyone say a phrase like that with a straight face? And exactly how did it prove [past tense] to be a great service that soon [future tense] encompasses mobile. Why would you even mention mobile in this context except because your working from a sheet of buzzwords?
This was a great way to purchase DLC and Now with the Games On Demand Service another outlet to sell the game.
You as a customer are deeply excited by Microsoft's buggy play-money transaction systems? No one who was an actual PC customer of FO3 would say that it had a great way to purchase DLC. It was a tortuous process of registrations and sign-ups, buying play money that didn't come in denominations that were even divisors of the purchase prices, and in many cases simply didn't work. There were over a dozen points of failure in the process. There were people desperate to pay money for products but were unable to because of the multiple layers of redirection misdirection, and ancillary software involved.
Here's a great way to purchase DLC: provide a credit card number, receive password to download full unencrypted content over a plain http link. No play money, no download managers, no forced internet connection while playing a single-player game.