Windshields and warriors

I've been thinking about the role of monsters in games, particularly with the recent Diablo discussion on Roguelike Radio's comments thread, and a recent attempt to play Torchlight (which for some reason had lost a whole lot of my character's progress). I'm also coincidentally at a point where I'm not finding gaming terribly satisfying: I suspect because I'm wading through sub par games like Deus Ex: Revolution, while waiting for the next brogue, Binding of Isaac, Terraria or Dark Messiah of Might and Magic to catch my imagination (to name some gaming highlights of the last few years).*

My favourite games have something in common: monsters, and enemies in general, exist in those games as an obstacle, not a resource - whereas Diablo, Angband and many others have you exploiting monsters for loot and experience. I realise Terraria requires you farm drops to find certain items, but boss monsters and Skeletons aside, you're almost always (until after the Wall of Flesh) better off searching for chests to get the same drop.

Jeff Lait used the analogy of 'windshield' monsters while discussing the fact that most monsters in most roguelikes are designed to be spattered with minimum effort while on the way to the end game. I'm not convinced that this is the case: brogue for instance has very few monsters you can safely ignore even while you are deep in the dungeon. Windshield monsters exist primarily for flavour: they're one step up from the bats and rats you see crawling around Diablo's caves, but unless you foolishly let your guard down and get mobbed, you're unlikely to ever die to a windshield.

brogue on the other hand, has too many 'puzzle' monsters: in the sense monsters you can solve fighting for to reduce them to a trivial challenge. The two I'm thinking specifically of are pink jellies and acidic mounds: the former require you fight in a doorway and always attack the weakest split, and acidic mounds require you fight naked, but there's also the list of monsters you typically keep negation for.

So assuming puzzle, exploitable and windshield monsters are not satisfying challenges, what should a typical monster do? In a finite resource game like brogue, or the Binding of Isaac, it is easy. Monsters should exist to consume your resources: either health, or consumable items - slowly wearing you down for the final fight, but only if you underperform in killing them (the Binding of Isaac) or if you are not able to evade them (brogue).

In infinite resource games like Terraria, their function is less satisfyingly clear cut: you can always grind yourself against the resource cost of more powerful monsters because the rewards in these regions are much greater as well. Terraria balances this by making the most valuable resources (minerals) acquired only through mining, which is higher risk than emptying chests, and gives you no immediate pay back, so it is possible to end up with a short term resource deficit which outweighs the long term benefits of what you have acquired. There's also a clever (or frustrating, depending on how you look) set of gating mechanics which forces you to traverse certain challenges before you can get higher tiers of equipment: some of the tiers are optional, which makes for a lesser game IMO.

* I'll be posting a 'help me pick a game to play' post separately. Day Z is a good candidate.