Let’s be honest, the bass and the bassist in general isn’t the focal point of most bands, with the pesky singists & guitards usually occupying those roles, so I think the hat thing is a “hey, I’m here too”.
Much like when I used to wear shades on stage in a glam-sleaze type band, it was a pee-take of the 80s look but also a way of saying I am here, look at me!