I very much agree that easy companion inventory access would be great. Ideally some kind of overview similar to the party overview but for all companions in camp.
As an aside, there is a workaround for checking inventory and transferring small amount of items from non-party companions. Just go into sneak and pickpocket the companion, you'll see their whole inventory and (as far as i know) you can "steal" items from them without repercussions.
