yes it is.. because touch screens are scratch magnets.. and scratches blurry the glasses/screen if u do have protector you can change from time to time when it gets blurred
I always use screen protectors...Always...on everything that has a touch screen. And I still use a soft cloth to clean them. I'm a little CDO...that's OCD in alphabetical order.
I think it depends on the phone...and probably also luck. I used a screen protector for a couple of weeks when I first got my phone, but once it started peeling at the corners, I got annoyed and just peeled it all off. Then I got used to the feel of the screen without the protector, so I never used one again. It's been like that for over a year now, and I have no problems with it whatsoever. And I don't baby my phones at all and I'm not that careful with it either: I've dropped it (and it's bounced haha) several times and left it in my purse with no issues. I'm on a Samsung Galaxy S.
On a contrasting note, when I first got my iPod Nano couple of years ago, I scratched the screen before I even used it. I didn't really care though...'cause it's not like that affects its performance or longevity in anyway. And having a perfect looking scratch-free device isn't gonna do anything for me at the end of it's life (I wouldn't ever re-sell it) either. I would've been neurotic about these things when I was a kid, but I've since then trained myself out of it.
For me, if a phone has a screen more than a tiny little thing like on a home cordless phone, it's a requirement. Regardless of what kind of glass it is. I also keep it in a hard case, then in a soft pouch. These things cost a fortune, so I make sure they're protected and insured!
There IS a trick to installation and it's not a quick process. I run the shower for about 10 minutes with the bathroom door closed to kill some of the dust in the bathroom. Then I sit at the counter or the toilet with a book under me and I go very slowly with a little squeegie that came with the screen protector and go super slowly.