When did durability stop being a factor used to assess a phone's quality? As someone who is somewhat accident prone (and who doesn't want to spend too much time fretting about protecting my phone), it's something I care about.
Granted, I don't this should be as big of an issue as some people are making it out to be, but I think the discussion should go beyond chastising owners for putting their phones in the wrong pocket. That's not much better than saying "you're holding it wrong."
If the back pocket is "not supported", that's fine, but when support is pulled on anything that people use, (however obscure or unwise its use may be), there's going to be friction.