That's fine for leggy, 170cm tall ladies whose eyes are level with the locker. I was born compact. I hover at just over 150cm. And despite trying my best to travel light, my cabin bag is always quite substantial.
I have a small bathroom kit with my essential toiletries and minimum make-up items. I have cabin socks for comfort, a shawl and a sweater for warmth. I have my reading material - a book, a magazine, and an iPad.
If I'm on the way home, I'll probably be carrying a few duty free items - chocolates for friends, fragrance for family. If I'm travelling to a cold climate I will probably be carrying a thick jacket. It all adds up, but there's nothing I can do about it.