I agree strongly with the earlier posts that "
the weather sealing is quite reassuring" Off course it will depend upon your needs, what and where you shoot. If you like to shoot outdoor, and do not want to be restricted to some nice weather conditions only, then WR is a must.
Your post however queries both the camera and lens WR. In my opinion, the WR body is a requisite. For lenses, there are WR lenses. There are also some very solid lenses that are sturdy and that can take a lot. As long as you take good care (TLC) to the lens, a sturdy lens can take a lot...
Most Pentaxians will add that a further major risk when working outdoor or in rainy/dusty conditions is the lens swap. It can be very tricky to swap lenses in bad weather.
I work a lot outdoor when I cannot restrict myself to nice weather conditions. My prefered setup is a single camera-lens setup : ie I do not swap lenses. Some Pentaxians use two camera bodies to have two lenses but avoiding the lens swap.
Hope that the comment will assist....