Keeping hair strands dangling dowanwards prevents the tangling that occurs when you lean over a bathtub then stand back up. In addition, you can have a shower at the same.
Black hair can be very delicate so if your shower produces water at a very high pressure delicate hairs will break.
Have you ever seen dirty walls and garden floors being cleaned using a strong jet of water? That shows just how powerful water under pressure can be.
If your shower's pressure can be adjusted, lower it a little bit when your head is under the shower just to make sure you don't incur unnecessary breakage.