In the end, riding in the rain is about attitude. If you look at it as a hardship, it's going to be a hardship. If you see it as just another riding condition, it will be a lot easier. And if you choose to embrace the rainy weather and welcome it, you might find a ride in the rain can be quite pleasant.
One of the best rides I've ever had has been in a heavy rainstorm. Each time a car passed me, I felt sorry for the people inside because they were missing out on the experience.