I deal with having actual OCD (not pop culture OCD where things have to be neat, but the OCD where I have to touch my light switch twenty times).
I spent so much money on cases for my old 4S, and with my 5s, I'll be leaving it out of the case.
All it really takes is a change in thinking.
Once I got into guitars, I started to really like that 'worn' look that guitars get after a lot of good use, especially Telecasters. My Tele has so many scratches where my belt buckle hits into it. I've accidentally hit it into the table while in the studio, banged it a couple of times, and such.
I take care of my stuff. But the metal outside of the iPhone is the case. It's there to protect the internals. If it gets scratched, it's doing it's job.
And as long as you embrace the scratches and stop worrying so much, you'll really enjoy your purchase.
That's not to say that I'm not afraid of shattering the screen, so I bought AppleCare+. The fact of the matter is, most slim cases that people like to buy don't protect the screen from shattering.
If you're into cases to make the phone more comfortable in the hand, then by all means that is an excellent reason to buy a case or two.
But for me, the amount of money that I spent on cases in the two years that I owned my 4S far exceeded what I paid for the AppleCare+ for my 5s. And I like the way the phone looks, and when it does get scratched, it'll be my scratched phone.