Screen protectors?

Do screen protectors actually help?
Do they reduce the sensitivity of the touch-screen ?

I had the Verizon rep install my screen protector based on their recommendation.  But after 2+ years my iPhone screen never got visibly damaged, even with my keys scraping against the screen in my pocket.  Supposedly the new screens are even stronger.  The iPhone touch screen was failing, but I don't think that was something a screen protector could have fixed.  When the screen would stop responding I would have to lock then unlock the phone to fix it.  There were no bad spots and no inaccuracy, so I conclude it was electrical or software.

I think the touch screen on my phone could be more sensitive, although it is adequate.

Post your thoughts:
- Do screen protectors really help?
- Do they have any downsides other than bubbles?