USB 3.0 has been around for quite some time, since it was released in 2008. But you don't see any simple microcontrollers with an internal peripheral that can do USB 3.0.
The Atmega32u4, a simple 8-bit AVR, has an embedded USB2.0 phy inside and only runs at 16MHz, as such it is obviously too slow to do USB3.0. Although there are Cortex-M controllers running at over 200MHz that don't have a USB3.0 peripheral! At this point, I feel like the clock for the MCU no longer matters. The lowest end processor I can find that does USB 3.0 is TIs Keystone MPU with an ARM-A15
Is it just taking a considerable amount of time to create the IP for lower end MCUs or does it require a clock generation (or some other) unit that isn't worth the cost to develop it for cheaper MCUs?