It's relevant. WR is not fool proof, but it minimizes the chances of water/sand damage. I shoot outdoors almost exclusively and often in rainy, steamy, moist, humid conditions (nature photography). I fried a Nikon D90 once when water got into the battery compartment. And I had a camera 'raincoat' on it. Since then, every body I've gotten is WR. And most of my lenses as well.
I spend quite a bit of time in limestone forests here on Guam - these are basically jungles with lots of rocky substrate. It's hella humid there, and then you have the corrosive ocean air on your way to and from. Not had any repeat leakage since. And I don't usually shoot in rainstorms, but I get caught in them - the WR gives me peace of mind that a short time before I get the camera into the bag won't be a problem. And yes, condensation - when I come outside, my cameras usually get covered in a thin layer of it. None of my WR Nikons or Fujifilm bodies or lenses have ever had internal condensation (not noticed it at least).