Subject: Is it a good thing to have more oxygen than nitrogen in air?

Dear Scientist,
my chemistry teacher had told me that we have a relatively large percentage of 
nitrogen in the atmosphere than the percentage of oxygen. But as we need oxygen 
in a very large extent, like respiration and buring fuels, etc, is it a good 
thing to have more oxygen than nitrogen in air? What advantages/disadvantages 
would it bring if there's more oxygen? and do we really need so much nitrogen 
in air?

I'm quite puzzled!
Thank you!
hope you'll be able to answer me!! ^^
Love, an eagar student

Re: Is it a good thing to have more oxygen than nitrogen in air?