Our "big" fights usually end up with many of the characters down and bleeding, but at the same time, I think the idea of some "perfect death ratio" -- one every 3 levels, as suggested above -- is insane.
Character death doesn't show that the campaign was "the right balance" of risk to reward -- death can just as easily be the result of poor rolls (which sucks if you're the dying character), poor tactics, or player stupidity... and sadly, the death isn't necessarily of the character suffering from the stupidity.... More on that in a second.
Personally, as a player, I like knowing that I *could* die, and then feeling like I was good/smart/lucky (in fact, all of those in the right blend) enough to avoid it.
In terms of the ability to raise the dead cheapening death -- I (mostly) agree. Now that there's no Res Survival or Con loss, death is a 7,000gp speed bump (5 for the raise, 2 for the restorations) -- which, yes, is costly (financially), but it also tends to encourage reckless behaviour that you don't see in games like Shadowrun, since you can just get raised again. As long as 1 party member survives, you all do, and all it costs you is coin.
[Resurrection and True Resurrection take this even further -- you can literally bring back the murdered king, and/or his father, grandfather and probably great grandfather too... (And this becomes one my biggest problems with games that have spells like that - why would anyone rich or powerful ever remain dead? Especially since (remember) reincarnation gets you a fresh new young adult body...]
Death may not be cheap, but it's not terribly expensive either -- at least not compared to the amount of coin you tend to have at those levels.
Having said all of that, though, a game where death is the final curtain *boom* with no recourse (especially a game where the line between death and life isn't all that wide -- and the 12-16 points most people get from their Con score isn't much when you're facing opponents with multiple attacks and strength/power attack bonuses of +12 or higher -- means that the GM popping a pair of 20s at the wrong time can completely undo years of character development -- which is pretty crappy.
That's why, to me, spells like Breath of Life, are brilliant (though maybe with a few extra rounds in which they can work) -- they allow for (some) correction of an "accidental" death without being a "get back to life free" card -- especially since if you were doing something stupid, you probably got severely overkilled, so the spell won't bring you back -- and so I find they do much to serve as that *good* balance.
But then, that's me.
Caveat the second: If your party's wizard or cleric aren't playing smartly, this can lead to the deaths of the OTHER party members. In one infamous party I was in, the wizard would enter combat on maybe the fourth round because of all the time he spent buffing himself before the first haste or fireball or whatever got thrown. By this time the fighter's down to half hit points, the cleric is just hanging on and the rogue is down. Other times, it's just inexperience or lack of familiarity with the rules.
Literally, my current players have been there. Twice. The party cleric (who is no longer the player of the party cleric), rather than doing anything useful, stayed back and let the rest of them go to the meat grinder. Twice, he was the only remaining conscious person, still with full (or near-full) spells, because he spent his time missing with his crossbow, for instance. (At the time, too, the party could only afford reincarnation, so we had some racial changes as a result...)
[In fact, the same player is now a martial-type (in fact, the primary meat-shield) and has similarly done bad tactical things allowing the rogue to get all but flattened by a Stone Giant. Fortunately, the new party cleric was there and able to make with the helping.]
