Well look at it the opposite way. A celebrity gets a hair cut and posts a picture, and it's suddenly a front page news story. Anyone else posts anywhere about their haircut, and suddenly they're attention whoring.
I have never seen a newspaper put a celebrity's haircut on the front page. That only happens in tabloids.
Also, they want to sell copies, and they're more likely to do this with content people are interested in. Celebrities aren't famous for no reason; they have reputations that warrant people's respect/disrespect. Which means people are interested in them.