Microprocessors have been adding specialized components for a long time. A simple integer processor isn't very good at working with decimal numbers, so we have dedicated floating point units. Floating point units aren't very good at massively parallel tasks like image and video processing, so we have SIMD units. Encryption still wasn't fast or efficient enough, so now we have dedicated encryption instructions in our microprocessors.
Maybe one day we'll have dedicated IDCT or wavelet transform instructions in our microprocessors. However, you could argue that we already do, in the form of SoCs with on-chip GPUs and DSPs. Maybe we've already reached the point you want us to reach.
The original idea to do this came as a result of extrapolating this trend to add custom processing features to general purpose processing microprocessors in the form of SOCs. If you extrapolate out from the SOC, over time, the role of the microprocessor becomes less and less significant and that of the special function circuits more so. Khitchdee's approach was to start at the other end of the continuum.
Maybe one day we'll have dedicated IDCT or wavelet transform instructions in our microprocessors. However, you could argue that we already do, in the form of SoCs with on-chip GPUs and DSPs. Maybe we've already reached the point you want us to reach.