MLG operates MLG.tv, the #1 online broadcast network for professional level competitive gaming; the MLG Pro Circuit, the longest-running eSports league in North America; and GameBattles, the largest cross platform online gaming tournament system with 9 million registered users across the globe.
Keeping the Surface Connect port and making the Surface Dock compatible with the Surface Pro 3 in the process instead of replacing it with a symmetrical and reversible USB-C port is a tradeoff I posit Microsoft thinks is worthwhile at this stage.
A typical host PC might have two USB 2.0 ports and two USB 3.0 ports. The USB 2.0 ports might be used for a USB keyboard and USB mouse, but the user may have far more than two additional USB devices to connect to the PC at the same time, and many of those might be capable of USB 3.0 operation.