Because storage has been the limiting factor (for the power-user/business user) for a while. Now that SSD's have come, the biggest bottlenecks have been diminished but we aren't done yet removing "legacy crap". The step from AHCI to NVMe will allow lower latencies (2.8µs vs 8.5µs), it has a huge queue depth vs AHCI and it is better suited for current modern multi-core hardware.
And the VII Impact + 4690K/4790Khas support for all of this?