Individual, piecemeal solutions like discretionary payments for those who understand the system does not tackle the problem.
What about all the vulnerable people affected who are struggling enough to cope with day to day life, who are now expected to come up with council tax and bedroom tax? Not everyone is in a position to find out what discretionary payments are available, identify the right person to contact about it, fill in long forms, and then repeat again in a few months.
Many people with spare rooms didn't choose to live in those properties, they were assigned them by the council/HA. Most of those people can't now move somewhere smaller. All of this is out of their control.