Ouch! bleeding wasps

I read yesterday about a poor man that was out for a walk, minding his own business. When he accidentally tripped and fell into a bush / shrub. Unfortunately for him it was home to a wasp's nest. Out they swarmed and attacked him, resulting in his getting stung over two hundred times! HE was rushed to hospital and treated. But OMG that must be painful, and scary. That many wasp's swarming around you, must be hard to think that you will ever get away or survive. Made me think though, what purpose to wasp's actually serve? Any idea anyone? Bee's we need for the pollination and honey, but wasp's?