Why might a hippie have worn a t-shirt with bob dylan's picture on it?

A reason a hippie might have worn a T-shirt with Bob Dylan's picture on it is to show an approval of antiwar music.

Explanation:

   To show an approval of antiwar music

Explanation:  Bob Dylan was one of the most influential, if not the most influential, musician in modern music during the 1960's and 1970's. His lyrics were full of symbolism and anti-war messages. As such, he was very fond of hippies whose main idea was peace, and they participated in many anti-war events with messages of peace and love. Bob Dylan had ultimate followers, every statement he made about the Vietnam War, or a song with an anti-war message was taken seriously and accepted by hippies.

i confess that there are several parts of this constitution which i do not at present approve, but i am not sure i shall never approve them: for having lived long, i have experienced many instances of being obliged by better information or fuller consideration, to change opinions even on important subjects, which i once thought right, but found to be otherwise. it is therefore that the older i grow, the more apt i am to doubt my own judgment, and to pay more respect to the judgment of others.