I've limited it:
I've adopted Eberron's plane of death thing: Entrapment (though it doesn't say it explicitly that it also applies to dead) with a Will save, or you'll lose your will to leave. And used Heroes of Horrors "something can go wrong" rule. This means PCs have a chance to get raised, but it's risky and can do serious trouble.
On the other hand, I'm using action points to negate death (-9 and stabilized, though unconscious), so PCs don't die unless they're overwhelmingly stupid (blow all their action points, all PCs get incapacitated that way, or do something totally deadly, like jumping into lava).
Cheers, LT.