Agree. Someone should add this into client. Everything that can be done on client side shouldn't be implemented in core.
A checksum feature implemented in the client lowers the chance that the client messes something up.
As far as I understand, the request for a checksum was made because ppl were experiencing a problem where money was sent to accounts that they did not enter.
So, you seem to assume that the cause of the problem can not be in the core?