i think that speed has nothing to do with songwriting, and in most cases i think it can sound a little out of place. i personally think that playing fast is a way to show talent. it doesn't neccesarily make one person better than another, but if millions of people can all write amazing songs, but one of those millions figures out a way to also play faster than any of the others, than who do you think will be held in higher regaurd. it is no different thatn people trying to write better songs than each other... it's simply a tool to be used to standout from the croud.