Theft of in-game items

With the majority of MMO's being classed as roleplaying games is the theft of in-game items or money really all that wrong? I myself wouldn't do it but I have known a few people that do. For example if a person was to roll a need on an item he couldn't use and win it, should a GM take the item off him simply because he lied?

CCP the company who owns EvE Online believes the answer to that is no. There is nowhere in their terms of service or use that says you cannot steal items or money from other players. The only exception would be if that person was stealing money to sell for real currency which would result in their account being banned. The BBC recently covered a story where a player in EvE robbed a bank in the game of 8% of it's value and sold it for real money. You can read that article here.

Blizzard on the other hand don't look kindly upon people who do it but are selective about who to come down on. Depending on the case they'll either take the item back or they won't.

I wouldn't like for someone to steal an item on me in the game and probably wouldn't play a game that openly condoned it but since it is a roleplaying game, the thought of being a thief isn't so absurd.