Conditional modifiers will always need to be better than unconditional ones to be useful. Some conditions are fulfilled often enough for them to be quite useful, like carrying a Grimoire. Others are too rare to be normally used (e. g. last man standing). Some are between and the real usefulness depends on the actual effect and interaction with other stuff. Running out of ammo on a primarily ranged character (who produces more ammo all the time to boot) is a useless contingency. While being disabled happens often enough (it seems to apply to being downed, too), and being able to stand more damage in that state is useful, allowing your buddies to kill your disabler faster isn’t, as if they cannot kill it normally before you’re out of the picture, they aren’t likely to do it with added damage either.
As @Licious-D said, having a conditional thing that depends on you failing (and honestly, having to be rescued is a major failure) is bad, especially if there’s another option that can prevent that failure. In this case, Respawn Speed is in Trinket, and there competes with several of the game’s best Properties: Crit Chance, CD reduction, Movement Speed, Curse Resistance, Stamina Recovery and even Revive Speed (which would be good enough if not for its competition). And as one slot is nearly always occupied by Curse Resistance, this leaves five better options that are either simply stronger or far more often useful.
And yes, there’s a lot of stuff to be tweaked in Traits and Properties too. No need to go any deeper here, the topic is about a single Property and there has been conversation about other balance problems before, and will be later. I’d suggest at least waiting until the next big balance update.