Well, we have moths that are adapted specifically to smog-covered cities, and their particular shade of grey would get them eaten in the wild.While this is true, it's not exactly applicable: we don't have animals that look like artificial structures,
...and your point is?who survive exclusively off of human explorers (because other animals don't pay much attention to treasure chests). The mimic is a monster aimed directly at PCs.
Very much yes.
I've had special case npcs dozens of times in 3E games. And yet the basic system of npcs and PCS working by the same rules persists quite excellently, keeping intact all the sense of the PCs being *part* of the world. 4E has jettisoned so much to "give" me something I already had. Very disappointing.
To me- playing all editions since '77- I just never liked the idea of NPCs having access to something the PCs never could unless there was a specific and meaningful (non-arbitrary) plot based reason for it- an item that requires a particular bloodline to activate, for instance.
Also, as I stated before, its easier (for me at least) to balance encounters when all of the NPCs go through the same "accounting procedures" as do PCs.
This is one of those things that really kept me from getting the most out of the game when I was younger. I had a very simulationist bent, and I too often tended towards the “if it isn’t explicitly permitted, it’s prohibited” mindset.
I’ve found I enjoy the game a lot more since I’ve tried to move away from that.
This is a difficult question for me as well.
I like my NPC's to have a certain leeway with what resources they have available, what they know, and what they can bring to the table for/againat the PC's. However, in running a game I am trying to create the sense of a consistent world.
If the kobold in Mouseferatu's post (able to cast raise dead) were merely able to use "raise dead" on an off-scene event (to trigger a plot, for example, where a PC's nemesis is brought back to life) I'd have no problem with it. There's no consequense other than plot. If the kobold couldn't raise the nemesis, I'd have somebody else do it.
However, if the kobold with raise dead were using it throughout an adventure, bringing back its tribe as the PC's advanced to wipe them out, this causes some issues for me. The PC's will rightly wonder "how is he doing this?" and let's say they figure out he is casting raise dead over and over. There are obvious questions that follow... like, how do we prepare against this high-level spellcaster? How is he obtaining the riches needed for this casting? If we defeat him quickly, perhaps these riches can be ours? (I'm talking in 3E-speak because I don't know how the rules for raise dead work in 4E)
But from the DM's side of the screen, this kobold is just a low level dude who can cast a high-level spell. So the PC's over-prepare, find no riches related to raise dead, and are unsure why thiings went so differently than expected.
What the players take away from this sort of thing is a sense that they can't trust in their knowledge of "how the world works" enough to guide their tactics. I have found that when the players can't rely on a consistent setting, they are less invested in that setting. As a DM, I really don't want that.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.