See no one has mentioned the questionable practice of the buying and selling to yourself that every exchange I have ever tested it on allows you to do. A nice bonus feature for the market manipulators on all the exchanges.
Anyone could easily get around a rule like that by using multiple accounts. It'd add complexity to the system and only effect honest users.
I've never tried to manipulate things that way (I don't think it would work too well), but since everyone knows it possible and can do it themselves I don't see it as a problem.
What honest user is buying and selling to themselves? It would not effect them in any way and if it is such a non-problem why has it been legislated into law for just about any exchange that is in existence. You know them puny little things like the NY and London Stock Exchanges.. This coin shit is just like gambling it is always nice to know your about to sit down at a rigged table or the dice have been shaved/weighted.