Do you really need a screen protector? I don't have one and my screen looks just great.
What happens if you don'y have one?
That's a question with a different answer for everyone. Do you really need to use a seat belt? Do you really need medical insurance? Should you install anti-virus?
With the advances in screen glasses, there is a lot less chance of getting scratches. If you are like me, my electronic gadget are usually in one of my pockets and I'm eventually going to rub it with a key, coin or pen. I'm also pretty good at dropping things which is why I use cases.
Bottom line is you don't really need one, but some day you might wish you had one.