What features would you expect from the game launcher/updater ?
Currently I have a launcher, that checks installed game version and newest available version. Download all necessary patches and installs them. Then there is a screen with game related news. It is possible to see patch notes, visit homepage, forum and chat. And of course, start the game.
The main reason for a launcher is the autoupdate function, so that a player does not have to check updates and manually download them.