Ninety percent of the photography I do is street photography. I am in New York one day and Philadelphia one day every week only to do street photography.
A *good* street photograph is inimitable, literally. It cannot be reproduced. The moment has come and you have either grabbed it or you haven't. That specific moment in time with those specific players interacting in that specific way in that specific light will never happen again.
A good street photograph is therefore entirely unique as an artistic form. In my opinion it is the highest achievement of photography because no other medium can do it. It is also the most difficult type of photography to do well and therefore, in my opinion, the most worthy of pursuit.