"hardware performance per dollar is growing at only a fraction of that rate"
Well duh, computing hardware is nearing the bleeding edge of atomic limits. The golden days where Intel's new generation of CPUs was >25% faster than the previous gen are long gone.
The only improvements we're getting these days is in making the hardware multitask its duties and throwing more computing power at problems that were handled solely by the CPU before. And we're already reaching the limit on how much more can be done on that.
It sounds crazy, but there will come a day when new hardware designs will become few and far between. Computers will come in several sizes and power configurations, and the choices will stay the same for decades at a time.
And I might yet see the beginnings of that in my lifetime.