This might just be your perspective. No idea your age, but personally as someone who was a teen/young adult in the 90s participating in the emerging rave culture, the 90s are dripping with nostalgia.
That being said, I have to agree that the word 'vintage' evokes the 50-70s more than the 90s. Maybe the word has just come to mean that era in the english language, just like 'olden days' tends to mean a pre/semi-industrialized era that's somewhat locked in time.
Perhaps we're running out of words for the past and we simply call these eras by their decades now.