Good is always a matter of point of view... bringing focus to a cause, making streets happier than they usually are or giving some fun for free to thousands of guys are good reasons to some people.
About the "really needed" thing, don't tell me that you only do things you "really need" in your life, I wouldn't believe you ;)

I don't do things I don't really need in the street making fuss all over it to people that have nothing to do with it.

Parade or not, others are annoying anyway