A building or structure should be desigend to serve a purpose, even a mine has some regularity in it, although here you can argue that the diggers followed some ore vein. But how is it that every temple floor plan looks like it is dedicated to the gods of chaos?
Quite.
This is something that has bothered me since I first encountered "official" maps/dungeons back in 1989 or whenever. The first person who DM'd for me drew her own maps, and they were all relatively realistic, and all made complete sense, and when I started DMing not long thereafter I did similar. Some stuff seems fine - high magic (an upside-down mountain or whatever) or exaggeration (corridors 20' wide when a real-life structure of that type they'd be likely 10' or less, quite possibly a lot less) don't really bother me, and indeed both can work well and be fun without really damaging immersion or whatever. I'm not too concerned about where the stone went in a world where it could clearly be magicked away in many cases.
But senselessness, that is an actual problem. Dungeons that are designed in ways that just do not make any kind of sense whatsoever, that don't serve any purpose whatsoever. They don't have a layout that matches even remotely with any kind of history or purpose they supposedly once had, even if they have any real backstory that makes sense, and many do not. Half-arsing it is particularly bad. Just monsters in rooms and traps and layout that makes no sense in something from the 1980s or earlier and which is at least cool in how extreme it is can be sort of acceptable. But you get these modern dungeons (including the first three official ones for 4E), which are just senseless drivel, whilst giving nods to realism (like humanoid monsters having a sleeping area) that only serve to heighten and highlight how nonsensical the overall setup is. The first 4E adventure is basically nothing but this, and there was absolutely no excuse for it in 2008. Almost every element of the dungeon, if you think about it for more than a few seconds, makes no sense, and some steadily make less and less sense the longer you think about it (the whole deal with the skeleton-summoning corridor was particularly nonsensical, even perverse, given the backstory attached).
Sentient creatures aren't going to live somewhere that doesn't serve a purpose to them, and aren't going to fail to modify it to better serve that purpose.
I think most people just completely don't even think about this stuff - designers and players - but if you're someone that does, it's maddening. I likewise just end up having to re-draw or re-do a lot of maps, or change how they're explained, or what is in them. And yeah it's also weird that some people seem to think "normal" maps are unacceptable. It bothers me as a player, too. I notice that it's extremely rare in modern games and relatively rarer in futuristic ones (as compared to medieval fantasy and the like), because I guess people think about things more naturally there.
I'd also add that sometimes you get "set decoration" NPCs who create the same problem of senselessness and highlighting the irrationality of the whole deal - most commonly some rando slaves who have been enslaved by some creatures but aren't actually like, doing anything. They're all just sitting quietly in the slave pen, even though they could be mining or cooking or farming or cleaning and tidying or whatever. And there isn't even a plausible "they'll be sold on" or "they'll be sacrificed" deal in most cases. And often how they (or indeed their captors!) are being fed is a complete and total mystery (and an explanation tends to be an expensive one).
And what seems really strange to me is that it's actually both easier and more fun to come up with these sort of explanations and make things make some kind of vague sense (it hardly has to be total) than it is to come up with random stuff for the sake of random stuff. Design a dungeon as a dead dwarven city and it practically draws itself (just collapse bits you don't need/want).
Reality + one 'what if' is the nucleus of sci-fi. Fantasy comes with a whole raft of baggage that doesn't dovetail neatly with reality, nor even, strictly logically, itself, at times, - but it's all familiar and intuitive enough if you let that impulse go.
