The main issue wasn't the lack of maps but that the game was so hard to map manually. They had to add additional areas just to make the map work.
There were some impossible/irrational room connections, but mapping them couldn't have been that hard, because I could always find my way without a map of any kind. This is bullshit anyway, because if manual mapping was really the main issue, then they could simply have fixed the impossible/irrational room connections. The main issue was adding a map because so many people were whining for a map.
Furthermore, these same people still would have been whining for a map even had there been no impossible/irrational room connections, as you well know.
Some people so in denial that there should be a maps in game - it's hilarious. I mean, If your "sense of exploration" can be ruined by a fact that people in Underrail will paint maps just as their ancestors from surface - maybe you don't had any wonderful feeling of exploration in first place? Humanity paint maps from dawn of existence and I see zero reason why inhabitants of caves and tunnels would refuse to do that. More believable world > "feelings".
An automap that tells you exactly where you are interferes with the sense of exploration for the same reason that a hint book full of solutions will interfere with the enjoyment of a puzzle or adventure game. Being handed everything on a silver platter kind of ruins any sense of accomplishment, yeah. If you don't understand this, then frankly, you're a fucking moron. Fortunately for me, I have enough self-control not to click that button (and know most areas by heart anyway, so it's a moot point).
"More believable world" is a realism argument, and as is the case with nearly all realism arguments, you don't actually care about making the world more realistic or believable. You just want a map, and believability is a convenient (but ultimately bogus) justification for getting what you want. If your true desire were to make the game world more believable, I can think of dozens of touches that would do much more to make that happen than any kind of map.
Realism arguments are the go-to ammunition of people whining for developers to add various features, as seen countless times on the Codex, the Steam forums, various games' official and unofficial message boards, etc. In this case, enough of you whined for a crutch that Styg eventually caved in, if you'll pardon the pun.
Underrail society seems pretty advanced technologically. Why would they not have portable automappers?
This is another realism argument. Once again, if you genuinely cared about the world's believability, justifying automaps wouldn't be your top priority.
Good gameplay always trumps realism, and inclined features trump convenience and "accessibility."