I don’t know why people are scared of skulls.

I mean look at them :

They are always smiling.

They are basically harmless,in the sense that they can not cause any physical harm themselves;without any external help.

They can be used for a lot of things like storage of candles, warding off black magic (not sure if black magic exists, but skulls are mostly used to create such an environment), a makeshift cricket ball, protect brains in case of a zombie apocalypse, scare pesky and meddling kids,  etc.

I believe rock bands use skulls to promote these virtues of the human skull.