I always thought the opposite...since you can't eject from a helicopter, I always thought (and pretty sure I've been told) they are built to maximize survivability during a crash. There were survivors to both downed black hawk in Mogadishu.
Part of the reason other attack helicopters don't have them is that ejection seats in helicopters add complexity and weight for not that much of an increase in survivability, considering the usual flight profiles that these helicopters fly.
It makes more sense to focus on improving the survivability of crashes through measures such as collapsing seats and landing gear designed to absorb impact forces. With these types of improvements the crew of modern helicopters can survive even severe accidents without serious injury.