Comment by dachris
That's certainly not the only (and I'd also not put it as primary) reason for extending the lifespan.
Still, breaking one's hip in advanced age is often a death sentence as many people never get out of bed again.
When an old person breaks their hip around here, people say something along the lines of "we'd better hurry up for visiting them one last time".
There's also a lot of reverse causation here. Healthy people don't fall very often and when they do they generally don't break their hips. Falling frequently and suffering broken hips when falling are both general signs of poor systemic health and overall fragility which portend a short remaining lifespan regardless.