[archagon]

I don't know about buttons, but "how the metal/plastic feels" is one of the most important things about a mobile device. It's pretty much always in your hand!

[koyote]

About 90% of the people I know who own an Iphone also own a case for it.

So yes, it's always in your hand, but most people don't get to enjoy the feel, the thinness, or even the design.

[ChrisLTD]

That stuff still matters. When the phone itself is extremely thin and light, a case won't necessarily make the combined package too heavy or large.