Don't know if this has been discussed, did a quick search.

Anyway, one thing always annoyed me about Oblivion or the other games, is that sure you could steal things, but where's the fun if you are the only one doing it?

It would be so much more immersive staking out a house for awhile, then you either see someone going in that shouldn't be or the item you wanted was gone when you tried to steal it, maybe the thief could leave evidence for the player to track him down?
Although that sounds more like a investigator job, it could be used for stealing an already stolen item.

Would be interesting.

Interesting, but I'm worried this could lead NPCs stealing from my own house.

Or friendly competition where you boast about how much you've stolen when drinking in a thieves guild specific inn.

Well making a companion stand guard would solve that?

Kinda like that one mission where you have to steal a book first in oblivion.

Yeah, it would be cool, but I don't see BGS making the same quests over and over again. They need to make up some new ones...

http://www.youtube.com/watch?v=us9ox2pMWzw

This makes me

It would be nice if I weren't the only criminal in all of Skyrim . . .

See someone else break into a house you were about to, only to call the guards on them and then trying to steal the item yourself, while the guards are occupied with the other thief, sounds kinda fun. Of course, that's when you come sneaking out with a stolen item, looking back at the busted thief, snickering, only to walk into grinning guard, "You buffoons couldn't make my job any easier. You're coming with me, CRIMINAL SCUM!" Then after both you serve your jail time, the Thieves Guild contact both of you to join the more organized Thieves Guild and its connections.

Thieves guild rules, can't steal from other members.

Why do people think realistic is a synonym to immersive?

What if we're not in the thieves guild?

I don't want to have to join in all my playthroughs just to stop my house getting broken into.

Well its a lot less total immersion, but a game is still an experience and i believe this would add to the experience.

Much more so with large games like this.

http://www.psychologyofgames.com/2010/07/27/the-psychology-of-immersion-in-video-games/