How necessary is a screen protector?

I'm on the mind that an ounce of prevention is worth a pound of cure.  So that
no matter how careful I might be, there will always be wear and tear eventually
on the device.

My previous phone (Blackberry 8830) was my pride and joy. Even though I did
not use a screen protector and was really careful.. Stuff happens and I regret
that I did not spend the $$ to ensure that the screen remained unscratched.

As far as screen protectors are concerned, the quality of the protector makes a huge difference. I picked up one of those mall kiosk ones for $10 just help prevent against scratches (my curve 8330, even though treated well, still got scratched up). I found that my finger didn't slide quite as well on the protector as it did on the glass, but finger prints don't show up as easilly, and I quickly adjusted to the difference in pressure. I don't feel that it made the screen any less responsive, but your results may vary with different brand protectors.