The problem isn't the quantity of characters disallowed, it's that they cover some reasonably common characters in tags. From the list of restricted characters on NTFS:
\ / : * ? " < > |
There are a lot of artists, albums, and songs that use the forward slash (AC/DC, Less Than Jake's
TV/EP), colon (Bandits of the Acoustic Revolution's "Intro: This is a Call to Arms"), asterisk (some releases of Serj Tankian's "Beethoven's Cunt"), question mark (Arctic Monkeys' "What If You Were Right the First Time?", David Bowie's "Life on Mars?"), and double quotation mark (David Bowie's
"Heroes", Fall Out Boy's ""Tell That Mick He Just Made My List of Things to Do Today""). As a stickler for having a well-organized music library, not being able to use those characters in my organization would be a bit grating.