I think interest rates have been too low for too long. Yes, it has encouraged spending, but methinks too much spending as I have seen friends and family totally overextend themselves on huge loans for huge houses just because they could. Even interest rates move up even 1%, they will be pushed against the wall to try and service those loans, and that in itself may trigger massive sell offs and bring housing prices crashing down.
It's basically a tightrope walk across a windy gorge at the moment - everything is precariously balanced, but for how much longer??