On an unconcious level women are always competing for the males around them. The result of millions of years of evolution. Long hair on a woman has for the longest time been a sexual attraction factor for males. It is said to represent a good genetic and healthy candidate to mate with.
Many women, knowing that long hair on most woman attracts males like bees to honey, will (unconciously) tell their female friends (even their best friends) how great they would look with shorter hair. Some might not be able to stand the "Princess like" look long hair give to women or just don't have the guts to take care of their own hair if it would be longer.
They would rather try to bring other women to their level instead of trying to elevate themselve to their.
A Shame.
Don't forget... all of this is mostly unconscious. But it DOES happen.
Then there is also the hairdressers who if every women would wear long hair would be almost out of business. For this reason they "invent' new "looks" on a regular basis.
Do not forget this: The women considered to be the most beautiful on this planet, Fashion Models, wear almost all their hair long. At least bra strap length. There's a reason for that. They see less demand from the industry when they have short hair.
Long live women with the "guts" to have long hair!
Alain