They're "vintage" due to age. Everything becomes "vintage" after a period of time. They always sounded good. Fender's customer base rejected them because they were different. Just like they do today.
"Valuable"... not so much. A standard '83 Precision will sell for more than a Precision Elite of the same year. These basses can still be had for reasonable money. They're one of the hidden values in the vintage market.
It was the white pickup covers.