That said, the suggestion isn't that far away from some of the run-time power-management approaches being worked on, where unused hardware is shutdown, and scheduling policies regulate what can execute while the system is "running". This would ideally, given proper hardware support, allow the same power-efficiencies as suspend when the system is idle.
I think both approaches are important. Runtime power-management makes the most of hardware features to save power while minimally impacting system latencies. While suspend power-management further restricts what the system will respond to, but possibly greatly increasing latencies.
If suspend/resume gets fast enough, and run-time power-management features in hardware get good enough, the two approaches might converge. And choosing which to use at that point might be a wash. But for now, I think its important that we chip away at the power-saving problem from both sides.