This sub-forum is for controversial threads. I think this link will answer your question Why are there lights on vaccuums? /thread
I did a google image search for "Seinfeld Facepalm" but came up empty. I did find this though, so what the hell, enjoy.
It is used as an emergency beacon if you are stranded on an island and happen to have your Hoover vacuum. That island should be equipped with a plug (probably in a palm tree). Plug your Hoover vacuum in and wave it around, your beacon should attract a nearby cruise ship. Your welcome.
I agree they are really useless. Who vacuums in the dark.. Even with lights some people still pick up socks, bras, rubbers, vibrators. Toys,pens , pencils,super baslls etc.. I know because i do this in my job, unstop them that is...toke on..