Lots of people are asking the question as to why many manufacturers do not produce interfaces that specifically utilise the USB 3.0 protocol.
Firstly, although USB 3.0 offers greater bandwidth than USB 2.0, it will deliver no round trip latency benefits over USB 2.0. This is due to the architecture of the host computer driver stack and its handling of USB audio (isochronous) data. The stack schedules data transfers to and from audio drivers at millisecond frame intervals which means that, no matter how fast the data moves over the USB bus, this defines the limit on minimum latency achievable.
There is also a question of backwards compatibility. Currently, most computers still come with USB 2.0 ports as well as USB 3.0, and many users still work on systems that have no USB3.0 connectivity at all. USB 2.0 devices work without any issue on USB 3.0 ports, however the same cannot be said for USB 3.0 devices on USB 2.0 ports.
With the question about backwards compatibility, combined with no real benefits to round-trip latency performance, the USB 2.0 protocol is still the most efficient technology for professional multichannel recording for the channel counts our USB devices provide.