Water resistant (e.g. ingress protection) phones (e.g. Xperia Z1/Z2, Galaxy S5)

Yesterday, I went out to a lake in the suburbs and went on a boat to fish with some friends - the day started off nicely, but it quickly became apparent that it was going to storm - and storm soon. I then realized that I was worrying quite a bit about my fairly new HTC One M8, which is rated IPx3, which offers little more than splash protection. I then started thinking about the new GS5 and the Xperia Z2, which are rated IP67 and IP68, respectively, and realized how powerful a water-proof phone can be.

As it turns out, we didn't get caught in a heavy down pour as we noted some lightning and got out of the water before the storm hit us; but still, I realized that I was worried about how my phone would fare if we did get caught in a downpour. I'm more than happy with my M8, but situations like this show the allure of a device like the Z2 or GS5 that really do have some merit; before, I thought it was a gimmicky feature, but being in danger of being soaked really helped me realize how useful IP ratings can be.

So, to owners of a water proof or water resistant phone - do you actively use this feature? Do you show it off, or do you have a use for it for more practical reasons (such as working outside)?

For new buyers, is water-resistant design something that you look for as a must-have feature, or is it still one of those things that is a nice-to-have, but doesn't influence your decision?