Daryl hall always wears the sunglasses just for the cool look. Besides the function of protection of our eyes from the uv rays and bad lights, you could find that sunglasses could also be used to improve your look. Wearing the suitable sunglasses and good clothing, you will look so cool and special.
Well, it seems that you like daryl hall very much. So, as a matter of fact, he is one of the most famous rock music singers in America, and would like to wear different sunglasses from time to time. So, as you can see, sometimes singers would like to wear them so as to be cool and remain mysterious and they would like to protect their eyes because sometimes there are many strong lights on the concert hall. Or it is due to their personal habits.