I didn't say constant rain. Near-constant rain or drizzle, or just rained, or about to start. At any rate, even when not raining the roads are usually wet and puddly. Rainy season temperatures usually between 20-60 F. Staying warm not such a problem as I work hard at pedaling. Good ski gloves, layers, good rain jacket with good neck wrapping, jeans (maybe with thermals underneath when temps are in the low 30sF or below). To try to stay drier (not really possible to stay completely dry) I will include water-resistant nylon overpants, a thin nylon helmet cover, and neoprene overbooties. There is a balance between keeping outside moisture out, and trapping perspiration-based moisture in.
Plus Full Fenders, or even a little more than what you normally imagine full fenders to be. Wider than the tires, and extending further down front and back of the tire that what is normally marketed.
Yes transportation mostly.
Worst casualties: Increased chain and bearing maintenance (wheel, BB, pedal).
Heard this somewhere: "There is no such thing as bad weather, only bad gear."