I would argue the liability is on both sides, not just on the person who pays alimony. Society has exceptionally little ways to welcome stay at home parents back into the workforce. If a stay at home parent's spouse is disabled or killed in an accident (unfortunately common in car-centric societies) the entire family is now in serious, serious trouble.
"common" seems erroneously high there. For any given household with a stay at home parent, the working parent's lifetime risk of dying in a car accident is less than 1 in 100. The risk that they'll do it in the years working to provide for the household is likely less than 1 in 200. Meanwhile, the risk to divorce is around 2 orders of magnitude higher. (I'd agree that "divorce is common"; something that happens about 1% as often, I don't think of is common.)
If you're making relationship decisions based on statistical chances of separation you're already operating on a level of fundamental distrust. If you're planning an "out" in what ought to be a lifelong relationship then you're already not in it for the long run. Risk is part of what makes a marriage meaningful, you're mutually accepting that risk and embracing it for the good of the other.