In my opinion, women simply gave up wearing stockings and suspenders in general because ultimately there was a more comfortable, and practical, alternative.
Trousers are also frequently more comfortable, and practical, than a skirt - particularly if you are involved in an activity which involves more than just sitting around.
I don't know why you think you will get "shot down" for posing the question though, unless there is a sub-text to it... I think tights gained popularity in the mid / late 50s in the UK which is a heck of a long time ago and most people, even old-schoolers, have long since lost their curiosity (or disappointment) at the change!
My male music teacher, back in the 50s, used to wear knee-suspenders to keep his socks from falling down. When he hoisted his trousers to sit at the piano, they were on full view. Then artificial fabrics enabled socks with elasticity and 'grip'. I suspect most men who wore these suspenders happily ditched them, too.