zlacker

Maybe you never had an issue, but today's phones are quite a bit more water resistant than the removable battery phones of yore. You can dunk them in water and you're usually fine! iPhones, at least.

I'm not sure dust was ever really a problem for most people. Although, for those in sandy/dusty environments (deserts, some industrial situations, etc) I bet it was a problem.

More to the point, though: I don't think it has to be an either/or choice. Casio makes a crapload of 200M water-resistant watches that sell for $50 or less. This includes both plastic (G-Shock, mostly) and full-metal models (MDV-106/107). The secret is (gasp)... a frigging thin rubber gasket. I frankly don't see any reason why we can't have this level of water resistance in a phone.

We would have to sacrifice thinness and lightness, but not by much. I think a lot of people would happily make that trade.

>>JohnBo+(OP)
Well, the second secret is having a very rigid and precise interface between the watch case and back cover so that the thin gasket remains under the correct amount of pressure everywhere around the joint. This has been optimized at the small size of a watch.

On a larger object, this level of precision is harder to maintain. Due to spacing between fasteners or other flexing/distortion of the body, the gasket could be overly compressed in some places and loose in others...