personally, i'm very delicate with my gadgets. i used to use screen protectors with my phone, until i got frustrated with screen protectors.
I made the jump to using my phone without a screen protector after seeing my friend who has been using is galaxy S2 without a screen protector for more than a year and it is completely scratch free! until now, i have no regrets for leaving my phone naked.
Screen feels silky smooth, clarity is amazing. I don't plan to use screen protectors anymore for my phone

if you're a very careful person, then going without screen protector certainly is alright.
but if you're the type of person who puts his keys in the same pocket as his phone, then it's probably best to go with a screen protector

it really all boils down to whether you are comfortable or not using your phone without screen protector..
hehe i do leave my phone to tango with my keys and coins in the pocket, maybe thats why.. im thinking of buying the kraken case!