Have you ever heard of piracy?
This has nothing to do with piracy, it has to do with DRM.
Game bought on Steam: you pay full price, you have to download gigs of data (so if your internet bandwidth is limited by your isp you get to pay extra).
You cannot sell "your" game, you cannot lend it to your friend, you cannot play it if your internet connection is down.
If a patch comes out and you dont want to install it.....you cant play the game, you HAVE to install it.
If for whatever reason Steam shuts down, or their servers go down, hack attack or whatever....say goodbye to "your" games.
Steam fans falsely ASSUME that Steam would release a patch making the games free playable but they are under no obligation to do so and its unlikely they will do so.
If you want to buy the game from Steam thats fine, but if i chose to buy the game box, why am i forced to install and use Steam?
There are other ways of combating piracy, Steam forcing in Skyrim is not about piracy, its about inter-company deals and DRM.