Janet - I think you're right. I know for sure in my case, I love 90s fashion because I 'came of fashion age' in the 90s - that was my teens/early 20s, when I made all my own choices, had a bit of money to spend, etc.
I can understand for sure that the reverse would also be true - a difficult time would not inspire happy fashion memories, not least of all because that was probably the last thing on your mind in the first place.
I am a bit ambivalent about nostalgia in general - as much as I love looking back at these styles, I'm not one to glorify the past at all (I'm sure most of us aren't) - despite obvious problems today, I wouldn't go back. As Angie says, in a slightly different context, but nonetheless - ONWARDS. Always.