You should probably think of "what could go wrong" with your suggestion. One clear issue is that people can abuse any trading system by making more accounts to trade with their main account. Many have asked this type of suggestion but fail to point this out. Makers of online games know what can be abused from trading system and aren't going add such a system if they establishing limitations.

Also Oasis doesn't make anything to the game. All they do is just license the stuff from Tencent (China Server) who is in charge of adding new features as they were the first one who created Naruto Online.