I don't fear it, but I do avoid it sometimes.
I also often do long trips where I'll pass through dozens of different climate zones[*]
The reasons gdb069
gave are key - few drivers drive to the conditions and visibility is significantly reduced, as is traction.
The rain to most avoid is light rain after a dry spell of several days or weeks. The crud builds up on (and in) the road and it takes a little time for this to wash off during a decent downpour. But if you have light drizzle or rain that's more like a mist than rain don't go out for a while. If the gutters aren't flowing wait it out, the road can be very slick.
But do get out in a parking lot and practice. The thing that will save you most in rain is knowing how to apply your brakes progressively and knowing just how much you can throw your bike around. Being confident of what you can do and 'grooving' your skills (think wearing a groove in the floor by covering the same tracks so often) means instead of freezing up and riding straight into a crash without doing anything, you'll automatically
be able to brake and/or swerve and avoid it. Your focus can be spent looking for the best exit as your body just knows what to do and you don't need to think.
I recommend get out and learn about rain where you can do so safely, because if you're caught out in it with a long way to shelter you want to know what to expect and know your bikes limits. I like to avoid danger where I can, but I also like to practice and experience as many conditions as I can so I know what my limits are and what to do if caught out.
[*] In NZ, like in mountain areas, it's easy to get 2 or 3 very different climates inside of 20 miles, eg your side of the mountains may be fine, the other side may get heavy rain. Or your side may be fine when you leave, the other side may be fine, but at the end of the day the last few miles home is in heavy rain.