My understanding is that there were performance issues within the Moors due to the large number of human operated characters jumping around, firing skills in the Moors. Turbine used a miniature player character design for the Creeps to get acceptable performance. Hence Creeps do not have:
1) Experience Points
2) Equipment slots
4) Auction Hall
6) Lots of other features.
Turbine decided to not allow any trading or sharing of stuff between the two factions even when the characters are on the same account. I have never seen any indication that Turbine wants to change this situation. It seems like any changes that I remember were to put stronger walls between the two factions.
At one time it was possible for a Freep to mail stuff to a Creep. The Creep could not get the item(s) because there are no mailboxes that a Creep can access. Eventually the item(s) would be returned after the timeout. Instead of adding a mailbox in Gram, Turbine made it so that no mail could be sent to a Creep.
A similar issue occurred with the Lotto. A Creep could enter the Lotto. Win a prize. The prize would get mailed to the Creep. No way to get it. Eventually the prize would be deleted when the mail timer expired.
Unless stated otherwise, all content in this post is My Personal Opinion.