I think you'd see more people playing rogues as "thieves" if they could.
But keep in mind that as an implementation I'd suggest that Pickpocket should be harder than steal (easier to get caught).
And if players kept their containers closed would require at least a couple successes (more chances to get caught).
As far as the suggestions go I'm ok whether or not stealing from a container would be blind (aka random), blind based on weight (aka can't steal heavy items), or open (aka players could peak inside containers).
Personally I like the idea of blind or blind based on weight. That's part of the fun of pick pocketing, you don't know what you're going to get