Because the message is coming from people they respect?
I find it unlikely that anyone who's decided to devote their lives to trying to prevent disease, car crashes, etc. is going to suddenly decide it isn't worth it just because someone suggested these things might be God's will. In fact, considering the time, money, and energy churches and religious people contribute to helping the victims of these and other tragedies, the idea that "This is God's will" doesn't seem to be any impediment to true concern or a willingness to help out.
Because these people have painful things they need to cope with, too?
Uh huh, and if "This is God's will" helps them cope with their personal crises, where's the problem?
If it effects their professional decisions, yeah I could see how that would be a problem, but like I said, I see that as unlikely, unless they're a bit touched.