Man, it's 2014 and this is still a debate?
Some people have small hands or are just flat out clumsy and drop their phones constantly. Those people probably need screen protectors.
Some people are just rough with their phones and throw them haphazardly into handbags, pockets, back packs, cup holders, drawers, and god knows what else phone will fit into. Those people probably need screen protectors.
Some people work in extreme environments such as construction and manufacturing which make it difficult to use the phone carefully. Those people most definitely need screen protectors.
Some people just have extraordinarily bad luck and mysteriously get bad scratches on their phones. In that case they're probably screwed as something else terrible will likely happen to the phone, but a screen protector may help.
Bottom line is that is an individual, case by case decision.
Me personally, I've owned the OG Evo, Evo 3D, Evo 4G, and now the One each from launch and have never used a screen protector or a case. In that three and a half years, I've never cracked or even had a significant scratch on any of the screens. I did damage the LCD on the 4G by tripping over the charging cord and causing the phone to fall about 4' onto concrete, but that's it.
As such, I don't feel the need for protection on the phone. I like the feel without it (that sounds dirty). But I swear pretty much every person I know that has owned a slab smartphone for any significant amount of time has killed a phone by dropping it or at least spider-webbed the screen at one point, so I can understand why most choose at least a minimal TPU case or something.
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