There's a lot of comments around "Because if you wanted to pay online you had to pay" and... those answers are absolutely correct. But that's not to say that Microsoft weren't offering a useful service for your ten bucks.
Online gaming on PC was functional, but it also mostly sucked. if your lucky the game you were playing had its own server browser, and bigger multiplayer games let you manage friends lists, but otherwise you were using 3rd party apps like Gamespy to find games, and if you were trying to game with your friends it was an even bigger pain int he ass trying to get everyone together on the same server. If you wanted to use voice chat you were using another 3rd party service like Roger Wilco.
Services like Xbox Live just asked "What if he handled all this on the system level? Friends lists, notifications, group chat were all part of the OS, and worked seamlessly with any multiplayer game."
It was pretty revelatory at the time.
Having a woman character that exits for the sole purpose of being killed and, in dying, motivating the main character to do the rest of the story.