Why hugging? "The event is fun, well, because it is, as are museums. And, most of us can do with a hug on a regular basis – especially all over-worked, under-paid with little job-security museum staff." (more here)
They admit themselves that the day's name is "a somewhat flippant title", and it led to some entertaining responses online, (my favourite of which is this article "Many museum workers are introverts who went into museums specifically because they did not want to be near, much less touch, regular people. In fact, they often don’t want to be around their own colleagues either.") followed by a swift explanation on the Hug A Museum Worker blog.
It's also given a small platform to raise awareness of what benefits museums bring to the community and the broader stage.