Nope. We're back to the argument that each and every rule in a game is meaningless without a given context, that what truly matters is what the rules mean when they are used at an actual game table, and how, rather than consider numbers in a theoretical vacuum.
Nope. My examples are not edition neutral.
Whether the beholder will in effect use SoD or SSSoD effects will greatly affect the players' choices when they decide on a course of action, whether they go straight for the fight, or choose other possibilities. Same thing with a rust monster in front of you. Whether the rust monster destroys your equipment permanently or it is just temporarily incapacitated will affect player decision-making tremendously. And the fact that some threats are indeed, serious threats to the players' characters may prompt more variety on the players' parts in the way they handle such threats, rather than just say "aaah what the hell, at least I have that first save, even if I'm diseased, I could place a good one while you guys hit it too."
Your presumption here is that SSSoD means there's almost no chance of death though.
The math in 4e is pretty simple. 1 in 8 chance of death from SSSoD as a base. Presume a 50% chance of the attack hitting you in the first place and you're about a 5% chance (give or take) of dying. Multiply that by 5 PC's and you're looking at around a 20% (ish) chance of character death.
That's hardly insignificant. If there's a beholder in the next room, SSSoD isn't the reason I'm running away. I'm running away cos it's a freaking beholder and it's going to kick my ass eight ways from Sunday.
But, take it into 3e (or earlier editions, it doesn't matter that much). Assume, for the moment, a 25% chance of PC failure on a SoD attack. Multiply that by 4 PC's and you've got about a 90% chance of PC death.
That's not increasing tension, that's just suicide by monster.
It's not that I'm opposed to SoD, it's that SoD in many cases, particularly in cases where SoD is linked to an area attack, like gazes, aren't SoD, they're just die. It's not that I don't like the idea of instant death events, it's that the math works very badly.
So, I disagree with you Odhanan that this is edition specific. I suppose you're right that I might be more likely to choose to fight in 4e, since the chance of death is reduced, but, that's because I should never fight in earlier editions since any area of effect SoD effect is a pretty much guaranteed PC fatality.