I don't object to the implementation of game appropriate mechanics on stealing - if the designers want to limit pickpocketing a merchant to just pocket change and smaller items, while placing big ticket inventory behind a locked chest, guarded by Ninja's, and give you the opportunity to sneak past the ninjas, disarm and lockpick the safe and sneak away, or get caught and have the shit hit the fan, that's fine. In fact, Pillars of Eternity among other games had such mechanics to a certain extent.
What I DO object to is someone saying "because I don't want to steal, but can't refrain from stealing, it shouldn't be allowed for anyone, so I don't have to deal with the self conflict.
If I'm playing a Paladin, I'm not going to take advantage of ANY stealing mechanic, because it is not in character. If I decide to play an Urban Security Expert (read sticky fingered thief) I may try and steal the shoes off your feet.
Either way, it's MY choice, not anyone else's.
That is one of the defining differences between single player and multi player gaming.
And even then, I know plenty of MUD's where folk steal anything that isn't nailed down, whether it be from NPC merchants or fellow players. Again, your choice whether to participate in that game or not.