Bees aren't designed as suicide attackers by nature. Their stingers are designed to shred through other insects with ease.
However, this also means that when they come into contact with human skin, their stinger becomes caught in a way which they can't pull out without dying.
Wasn't that obvious? people do think that if bee's sting fellow bugs and small creatures they die the same way they do if they sting humans?
From day 1 I always knew that the reason the stinger got stuck on us is because of being bigger creatures with bigger mass and thicker skin, same happens with other animals of our size or slightly smaller.