Letter jackets used to be a pretty prized possession in many young athletes wardrobes. All of our kids had them, our grand kids have letted three and four time in multiple sports, but they show no interest in the jacket(s). Have times changed that much? Ah well, I've still got a few months to convince them they really, really want one! LOL.
By the '70s, at least in my NJ high school, a few athletes wore them, but they didn't really have the cachet that they had in an earlier time.We had white cardigan sweaters and pins that went on the big red letter for each year and each sport. I recall vaguely there was some special day, I believe it was Friday, when you could wear it to school. That was about all the use it got. I still have no idea why I hung onto it for years.
While athletes still commanded respect and the ultimate high school currency, girl's attention, it was long hair, jeans, fringe suede jackets, rock-band T-shirts, etc. that were really "cool."
Letterman jackets had too much of a pre-70s, "goody-goody" feel to them in that anti-establishment moment. That was just my impression from one high school.
Personally, I love the old cardigan sweaters with the stripes on one sleeve. I'd like to say they are a "timeless" look, but clearly, we are seeing in real time that nothing truly is.