My chickens are around a year and i collect their good feathers that they molt, but there are still a lot left. I also give my chickens baths so that they look good and keeps them with nice feathers.
Giving chickens baths is good, but they dust themselves also. Plus, you can get types of powder for bugs that you can dust your chickens with. When you dust them they usually loose feathers because at first they flap when you turned them upside-down, then you have to rub the dust into their feathers and it gets their loose feathers out. When you give them a bath with water and soap, they usually don't stink as bad afterwards.
People can keep their chickens feathers for crafts. They look good and it's fun! Two crafts you can make are a feather tree and you can put them inside a pillow case and sow it, and there is a lot of jewelry that you can make with them too: necklaces, ear rings, head bands etc. Also, since chickens molt quite a bit, you should have enough to always make crafts, and if you have a descent sized flock. There are various designs on chickens feathers also. Therefore, it can look unique. Last, when your chickens are done molting old feathers, bright, new, pretty feathers grow back.
But, some of the feathers are nasty and what you can do with them is put them in compost, feathers break down easily. The compost is good for your plants, then your chickens can go out and free range and eat the weeds from your garden, but they will most likely eat your plants too.
Chickens molting can be good and bad, but if you know how to deal with them then it can be fun and helpful.