It's not the hype, for me I use JavaScript because I have no choice. I dislike many things about it, but I have no choice, I need my code to run in the web browser, no plug in, no Flash or Silverlight etc.
For my start up, I can't see a single reason why we'd use PHP, try to not think of it as me saying PHP is bad, it's just other languages and frameworks offer us more value.