At first I didn't think your comment needed a reply… maybe you were joking or something.. but in any case…
Skyrim -- Having the game, saves, etc in my steam library is worth it. Not matter which computer I am on I have access to all my data. I do not have to worry about backing up the game files or keeping track of the discs.*
Skyrim Mods: There are many 3rd party game modifications for Skyrim. Some are multiplayer. Will they work with a pirated copy? Maybe but having a legit one erases that chance.
RAGE -- I like Carmac and the game engines he builds. RAGE has multiplayer anyway.
KOTOR -- I know nothing about this game but I keep seeing positive reviews and comments to this day about it. At 2.50 why the hell not.
*saved game data backup functionality via steam servers varies by game