I fail to see how "scuffs on the sides and back" are considered the phone's shortcoming.
Power problems I understand, and buttons not working, sure - that too. Anything else SHOULD be paid for by the customer - Apple does not have to cover your misuse of the expensive device they manufactured. Just because you got it for next to 0$ on some phone plan, doesn't mean it's not a sensitive piece of technology that you shouldn't toss around, sit on, expose to the elements...
I've never had a phone last less than 3 years. I was a BlackBerry user until January when I purchased my iPhone 5 - made more sense since everything else I own is Apple for work. I have a trustworthy case, and treat my phone as the valuable, sensitive computer it is.