And it's too hard to use "/me reaches a bulky sack to X, from which a metalic sound can be heard"?
I rather think that this feature will restrict RP. It's a way to make "non-RPers" look like they're actually RPing. If they don't mind to RP, I don't mind their "System"-messages either.
Those who take RPing serious, and also like to RP, will write something anyway.. and that in a much better way than any "generic" message can be. And IF they want to be the trade a secret, they will also RP it in such a way..
Tell-trades? That's pretty much OOC.. and their "X gives Y some Z" message will not really change it.
What if you want to trade something OOCly? For example during some RP, to get some item which one of them ought to have anyway. The "X gives Y some Z" message would be disturbing.
I really don't see a benefit for RPers.