Related: Fake explanation, Guessing the teachers password, Understanding your understanding, many more
The mental model concept gets used so frequently and seems so intuitively obvious that I debated whether to bother writing this. But beyond the basic value that comes from unpacking our intuitions, it turns out that the concept allows a pretty impressive integration and streamlining of a wide range of mental phenomena.
(Agree with what you are saying and add my take on it.)
I would say that the concept is explored, but this nomenclature isn't established as a dominant standard (nor expressed powerfully in this post). Part of the problem is that the post is written submissively and by an author without established status. We don't feel obligated to engage with him inside his way of carving reality, even though it isn't particularly controversial in describing how things work.
We already have the word map of 'map is not the territory' fame. The way (specific to human) 'Mental Models' would differ from and perhaps constitute maps of the territory is something that would need to be explored. But as you say we just don't seem to have the motivation to do so. The author acknowledges this in the first paragraph. In fact, that very paragraph more or less primes us to be unmotivated to explore while the final paragraph unintentionally gives us an excuse not to do so!
Hm, at risk of getting facial egg, how would you say it compares to my recent hierarchy of understanding, which got to +40, and gives a useful organization of epistemic states long discussed on this site?