Why is it fluff? I know nothing about Prince other than that he changed his name to a symbol (and that is because Eminem told me). Knowing that he used symbols in other ways could add context to his choice to change his name to a symbol.
I don't interpret the second clause primarily as evidence for the first. I view them as two related statements--
He was already known as provocative and strange; he'd already used symbols more than most people before.
This is important context to his strange move of changing his name to a symbol.
It's more longwinded than necessary, but it's not awful.
(Unless one finds the question "buy why mean it that way?" to be perplexing)
In the 1980s, it was indeed very strange to do that, especially in the official names of songs and albums. It was something kids or the illiterate did. It was embarrassing for an adult to use 4 for 'for' in anything important, even art. Today, that is not strange at all, it is common slang.
Prince is one of the reasons why we don't see that as strange today. He was one of the first to (re)introduce doing that on purpose in a major work of popular culture.