Why did Samsung make the phone water- and dust-resistant?
“Waterproofing” the Galaxy S5 was a bit of a no-brainer, really. The Galaxy S4 Active variant proved that Samsung could make a phone like this, which only raised the question: Why not just implement this in the first place? And so Samsung did.
Note, though, that Samsung isn’t claiming true waterproofing. It is, however, backing IP67 military spec, which means that the phone can stay underwater for up to 30 minutes at a depth of 1 meter, or about 3 feet. You’d better make sure that the back panel and your important ports are sealed, though.
Some phones can spend more time under the surface without damage, but the standards are there as legal protections and guidelines. (Here’s a cool little tidbit on the future of device waterproofing, by the way, with a neat little demo to go with it.)