I used mini for years when every peripheral used it. Broken a couple. Mini I have yet to break. Anecdotal, sure, but if you make a low quality plug, it doesn't matter what form factor it is, it'll break.
In other words, if the manufacturer uses a low quality micro plug, it'll break. But, if they use a low quality mini-plug? It'll still break.
One of my keyboards travel, so the cable gets detached a lot. It still gets plugged and unplugged a whole lot less than, say, my tablet. Which is a couple years old, and uses a quality micro plug. It feels plenty solid, just like the day I bought it.
And let's be realistic here: If number of insertions and strength of the connector were as big a factor as people like to claim, we'd be using neither, but rather full-size USB-A or USB-B. Not like there isn't room on the back of a keyboard for them.