Is pickpocketing an intended feature for 3.13, or is it an oversight?

It is a bug, unfortunately, yes. You can't roll Khajiit, you can't do sneaking, you can't pickpocket, unfortunately. So yes, it is currently a bug and hopefully will be resolved. But that's not to say that when we do local inventory, coming soon, you won't be able to steal other people's things. You just have to disable them first.