Imagine - one morning you wake up, go out and 70%+ of woman have bluntly accurately cut hair barely touching their ears with straight thick bangs and their napes shaved bald.
The world of absolute boner.
And if this would become a big enough trend in real life (70%+), then in fiction it would become highly prevalent too.
Just think about it - what if most of hentai had a girl with bowled bob-cut (and some veriation of that hairstyle) as main character(s)? Absolute sexiness.