Personally,I liked her hats and wore them myself.
Because I have ALWAYS worn hats,I can't put my finger on the exact date that women stopped wearing them much,but I think that it was after Jackie left the White House.
Part of the problem,was women's hairdos....falls and wigs became the "IN" thing and wearing a hat on top of all that hair,was just about impossible!
It seems now that the only time you can get a woman to wear a hat at church is on Easter Sunday. So sad. I wear either a hat or a scarf on my head EVERYTIME I go into a church. Doing my hair on Sabbath is too much work.