This is a great answer, but for some reason the author left out the most obvious of reasons. Mini-USB put the mechanical strain of the connection on the socket side, while Micro-USB puts that strain on the cable side. Since its much easier to toss a cable vs remove and solder in a new socket connector the average cycle lifetime became much less critical in general.
This was true of the first revision of Mini-USB, I'm told, but not subsequent revisions. The wearing components were moved to the cable while retaining compatibility with the older design.
The rumor of socket-side wear persisted well after the design change (all the way up to today, as evidenced by your comment, and many others) so Micro-USB was created to work around the confusion regarding Mini-USB entirely by simply creating a new connector.
For a few years I was bringing my Happy Hacking Keyboard to and from work every day, meaning (at least) 2 plug/unplug pairs per weekday. I'm kind of surprised it still works because it's pretty old.
I eventually got a second one which I leave at the office, but was kind of surprised that years later they hadn't replaced mini with micro. There are some mods people are building to replace the mini port with type-c, and I expect I'll try something like that when it eventually starts to fail.
Electro mechanical connection requires springiness action to be reliable - one side of the connector needs to work pushing pins together. In full size and mini USB elastic pins are inside sockets, plugs have rigid contacts
I can speak to this. I have a Google Nexus 7 tablet with the mini-USB connection which I’m no longer able to use because the port simply will not hold a cable effectively enough to charge it.
