Let's take a step back - Do you agree there is an implicit expression of 'guessing game' present in the 'map and key' term?
I guess? To an extent?
I described it above. Whether we call it "map and key" or "hexcrawl" or whatever else, it rests on the fundamental principle that the GM has secret knowledge which the players desire to learn so that they can make well-informed decisions. Are we agreed on that?
If so, then from there the question becomes:
how do the players gain that knowledge? They must ask questions and remember (or record) answers. This is a serious potential point of failure because, if the GM has done poorly, yes, it really can degenerate into a mere guessing game, "can you read the GM's mind to find out what you need to know?" To my ear, "hexcrawl" obfuscates this issue, making it sound as though there is not ever an issue of
how the players learn what they need to know. "Map and key" recognizes that this
can be an issue, without having it ALWAYS be an issue. After all,
maps exist, people make and use them IRL; we are often required to examine our environment and figure out the right questions to ask to learn what we need to know.
Hence, your objection seems to me to be centered on a distaste for recognizing that this playstyle,
whatever we choose to call it, is rooted in secret GM knowledge that the players must extract from the GM through the process of play. The players start out ignorant, while the GM is omniscient. The players must perform actions which induce the GM to reveal what they know. These actions cannot be trivial or the game is boring, but they cannot be nonsensical or the game is infuriating. "Guessing game" is the latter failure state. Refusing to recognize that it
can be a failire state is a problem. Likewise, pretending that this failure state is the
only possible state is also a problem. I don't believe "map and key" commits the latter error. I believe "hexcrawl" commits the former.
There is a fact of the matter about the world. It is, intentionally, obfuscated from direct player observation. The players must find valid actions (there need not be only one "right" action) which remove this obfuscation, so they may directly access the fact of the matter. The GM must make the obfuscation significant enough to be an actual obstacle worth overcoming, and yet not so much of an obstacle that it can't be overcome at all. Whatever term we use, we must recognize that these failure states are real risks.