Unless you're running disc brakes (which most road bikes don't have), your rims will not be happy when wet. Maybe the new ceramic ones are better but why should I buy a new set of wheels for an extra couple days of riding? Additionally, I like to have more than 2 square inches of rubber in contact with wet pavement, decaying leaves, mud, ripe olives, etc., etc.

My body will tolerate the rain just fine, but it won't tolerate the cars that hit it. Even a beater bike for rainy conditions won't change this.

So, you say, go mtbiking because you don't have these issues. I don't care to destroy someone' backbreaking trail building labor or start erosion problems.

As Tater said, getting caught in the rain is fine. Starting in the rain, no.

UK, check your bike's parts and specs. It is not completely sealed against the elements. Feel free to ride in the rain, but you will need to spend a lot of time over the years pulling parts, cleaning, lubing, checking the inside of the frame and replacing parts. If you're OK with this, have fun.

FYI, we had one 40 mile ride in the rain on our steel tandem. We found rust even in the eyelet holes for the bottle cages. It's fine but it brought home the fact that you have to strip the bike to the bare bones when you treat it this way. And, we don't even have salt on the roads like Idaho and Utah. Oy vey!