I always rock with a screen protector. My last phone had it's touchscreen all fukked up; not with scratches, but it became unresponsive/weird acting. While I've cracked a few screens, I've never scratched one, yet after that unresponsive/weird acting incident, I'll never go without a protector again. And since, after putting it on, it's really not noticeable, I can't see why anyone would risk NOT using a screen protector.
I don't do cases, tho.... Naked phones feel that much better.