Let’s face it: there are insanely improbable creatures in old-school D&D that seem to exist solely for the purpose of punishing GOOD play. Oh, your pesky players are making it hard for you to catch them off guard because they’ve started listening at every door? No problem, just hit them with a few Ear Seekers (termite-like creatures that live inside doors and burrow into a character’s ears and EAT THEIR BRAIN when someone tries to listen at a door) and they’ll get over THAT right quick. And that’s just one example.

All that said… our group’s characters in 4e are dropping like flies. It was rare for a character to go down at all in 3.5, but in 4 so far the ratio of characters in negative hit points to combat encounters is pretty close to 1:1 (if you count yoyo healing… he’s up, he’s down, he’s up, he’s down… more than once, then it’s higher than that). In one encounter we lost two characters, and another encounter left only one character still standing at the end; he had expended every available source of healing, and was half a surge from death.

So, I think both viewpoints may be correct here. DMs may be less inclined to do their utmost to wipe the party, but some of these supposedly reasonable encounters (they’re from a published module, so it’s not like our DM is specifically out to get us) seem proportionally a lot tougher.

The one constant as you jump from game to game is that it’s entirely up to the game master to walk that line between making things too easy for the PCs and for making things too hard. If he thinks it’s time for an encounter/adventure/campaign with a high mortality rate, he’s going to do his best to balance the probabilities involved to cause a high mortality rate. Where the module says, “4 orcs,” he might throw in six. Where the rule book says, “Paralysis lasts until the end of the victim’s next turn,” he says it last three turns. Where he could choose to pit your party against the fluffy chalk-drawing puppets of Sunshine Land, he instead chooses use Blooddrinker the Uber-Vampire Without Pity as your nemesiss for the campaign. And he can do all this without breaking a sweat, whether he’s playing D&D 4E or Steve Jackson’s “Toon”. This despite the fact that there’s no death in Toon — or at least there wasn’t, right up until the point the GM said there was.

MMORPGs may dispassionately generate random encounters with no concern for your PCs’ capabilities or history, but no GM worth his salt is anything close to unbiased. Even if he could pull it off, he couldn’t pull it off nearly as well as a computer does, so the conceit of the impartial human referee that Gygax envisioned as part of role-playing three decades ago has been slain by the information age. The GM is a storyteller, not just some guy sitting there to make sure his players don’t cheat, and whichever set of rules he uses, it’s just a tool to help him create drama. The rules system will have a profound effect on what components he unleashes to accomplish a desired effect, but he will always start with knowing the desired effect and select those components he thinks will best achieve it — even if those components are a set of random tables he chooses to delegate the final decision to.

This is like saying that you’d rather find yourself in a dark alley with Hannibal Lector holding a chainsaw than with Mother Theresa holding an AK-47, because the AK-47 is the deadlier of the two weapons. Until the DM puts you into a room with a monster, the rules don’t even start to kick in. And it’s entirely up to him whether you’re facing six kobold minions or six hundred ancient red dragons. The DM chooses the adventures. The DM chooses the encounters. The DM chooses whether you’re facing an underconfident coward whole faint at the first sight of a blade, or a bloodthirsty fanatic who’ll keep fighting for five hours after his heart stops beating.

The dice and the rules hold zero power that the DM does not imbue them with.