I actually use the waterproofing on my phone fairly regularly. I've used it to take pictures in and under water and it's handy to be able to wash it under running water. Also if I'm riding my bike in the rain I don't have to worry about my phone getting wet or sweat getting into when it's in my jersey pocket in the summer.

I think it will be pretty hard for Apple to design an iPhone with a removable battery without compromising somewhere. Making it waterproof, with a removable battery, not more bulky and with the same kind of sleek design sounds really hard. Still, it's good that the EU is forcing them to figure it out.