For some of us it's less that we drop it in the toilet and more that we are oppressed with inadequate pockets-- our pants are designed to cling to our bodies rather than function as pants-- so we have to put our phones in our back pockets and they don't really stay there when we have to slide out pants down to pee. I've also cracked an iPod when I fell on my ass. This could have also been solved by real front pockets. Ahem. Excuse the rantpage.
We talked about women's pants and pockets last night in irc. They seem very non-functioning these days. To the point of using their back pockets to hold their phones. Odd
It's for fashion. You get a cleaner line if you use fake pockets and using the pocket over time messes with the form of the garment. Not very practical at all.
Why have pockets at all then? I bet pockets are a thing of the past in 10 years for men and women. So much of what we normally put in them will be digitized and worn.