Having to trust GHash is completely beyond the point. What if they were perfectly altruistic, but someone held a gun to the operators' heads IRL while performing an attack? Removing the need for trust has the added benefit of removing responsibility to protect against wrong-doers.
good point its the same as the scenario of a pool that had 30% and another pool having 21%. some well organised guy can easily arrange to raid/bribe the 2 pools and get them to implement the same code. meaning a total of 51% of miners would be relaying new confirmed blocks that have nasty rules added.
the only solution would be a 10% cap that is put into the main protocol, that way pool owners have no choice, but to only get a 10% customer base/chance of solving a block and would require 6 pools to be collaborating/co-erst into doing nasty mining rule changes