Why forge? To get fees, but when u're forging, u're securing system. Way to get fees w/o securing not so easy to pick (u need modified code, and have that code updated), so greedy forgers'll exist and'll non-directly serve their key purpose (as miners today).
If you read the original post of the thread, the suggestion was to reduce fees to a minimum level required to prevent spamming the network, and remove the financial incentive to mine purely for fees.