The original mini-b port was rated for 1000 insertion MTBF (I swear one friend's cellphones were closer to 500, as they were going through 3 a year.)
It was revised to fail at 5000 MTBF, much more acceptable for something that may be plugged in multiple times a day.
Micro USB was rated I believe at 10k MTBF, and moved the faily bits to the cable.
The USB-IF obsoleted the Mini-A and Mini-AB plugs at that point (which are really only used for USB-OTG, which is rare). They still let the 5k MTBF mini sockets get certified on new devices, however.
I'm aware of the ratings, I'm just trying to say that in my experience, no matter what the numbers say, reality has proved the opposite for me, I've had far more (some number I've not counted, but, in the order of dozens) Micro ports/plugs fail on my than I've had Mini ones fail (none, ever).
It was revised to fail at 5000 MTBF, much more acceptable for something that may be plugged in multiple times a day.
Micro USB was rated I believe at 10k MTBF, and moved the faily bits to the cable.
The USB-IF obsoleted the Mini-A and Mini-AB plugs at that point (which are really only used for USB-OTG, which is rare). They still let the 5k MTBF mini sockets get certified on new devices, however.