From personal experience, build materials do matter. I like to use my phone with no case, and phones built with premium materials just makes you feel like you're holding something substantial in your hand. However, I do believe that functionality should come before the materials used, since it's not like the Samsung Galaxy line is horribly built. If both the HTC One and S4 ran the same software and had the same functions and feature, I'd bet most if not everyone would pick the HTC. It's not about the premium looks, but actually feeling like you're holding something solid, instead of ridiculously light and flimsy.