Considering that most of us are going to get new phones every 18-24 months I say it's not worth it. Yes, you will get tiny little hairline scratches here and there (that you can only see when the screen is turned off) but so will screen protectors.
Back in the Droid Incredible days I had a Zagg protector for a few months. It didn't feel very nice and ended up getting small tiny imperfections as well that I just ignored. If you are going to ignore the tiny imperfections on a screen protector then just ignore them on a bare screen! In my opinion, the phone is SO much better to use when the glass is bare.
I have insurance for the big hits so that I can leave my phone completely bare (no case, no screen protector). Made my experience significantly better day to day with my Droid Incredible, then my Galaxy Nexus, and now my S4.