In the rest of the electronics industry the mini USB connector has been pretty much been deprecated because (among other reasons) of the propensity of the socket to fail - leaving the user with an unuseable device.
This was taken into account when the micro USB connector was developed; i.e. the parts most subject to mechanical wear-out are located on the plug not the socket, so that all can be made new simply by getting a new cable.
As fewer and fewer PC's have included optical drives (or even half height drive bays at all), the most visible optical disc products these days are external slimline USB drives. I've noticed, though, that almost all of the USB 2.0 models continue to use a "blast out of the past" mini USB connector. (The USB 3 versions use a micro connector, probably because the USB 3 mini connector is a rare, ugly piece of hardware).
Any ideas why this might be?