Ask HN: Why I should attend to Google I/O?

I'm building a company focused on APIs on node.js ( a kind of Google Apps script but for all APIs -not only Google ones and not on Rhino as Google Apps Script-). Just to know why people attend to Google I/O. Is it only a google tech conference for discovering Google tech news 2 days before everybody? Is is a business networking event? Is it a "business with Google" event? Which population goes there? Only Developpers using Google technologies? Is it open to start-ups which can show off their techno? I would come from France to go to the Gluecon 7 days after, so I would like to know if I have a good reason to spend $900 to Google I/O (If I have the chance to book a ticket the 13tth of March !!!)