I think it is because of glam rock and wearing too much make-up. Men were a bit flamboyant, and they projected more of a transgender image with fishnets and ripped tank tops. Also, I think calling the singers of this time “ugly” is subjective and up for debate. At the time, men making themselves up as feminine was very fashionable.
There are some classic looks that still, to this day look fantastic. For example, some would consider Madonna’s look in her early days as trashy, but for the time, she was the quintessential 80’s sexpot. What was once considered to be bold and rebellious, now may look somewhat ridiculous and over the top.
Retro hairstyles look asinine today. Big hair from the 80's was atrocious and difficult to maintain. Also, people would crimp their hair and hairspray it to death. It was the era of excess. Lots of caked on make-up and tons of eyeshadow. Cyndi Lauper had a somewhat unusual sense of style.
She had big hair, which she would dye all assorted colors and it looked like a rainbow. Also in the 80’s, teen singers such as Tiffany and Debbie Gibson would dress in clothes that detracted from their natural beauty, and they would often try to appear older.