First question - did your hands come off the handlebars? I was taught as a new racer that hands coming off the handlebars after hitting something always leads to a bad outcome. In fact, we were taught to ride in the drops anytime we were in in "iffy" situation. (Behind a car or rider we could not see around and that we did not trust to lead us around potholes, etc. Poor pavement.. I ride in the drops when I am tired because I just might not see/notice something.)
I know now everyone rides on the hoods probably 90% of the time, but I don't see how anything has changed since 50 years ago except the hoods got a lot more appealing and the little safety item we had to deal with is now gone. (The brake cable coming from the top of the brake lever. All of us jammed our hands on that cable at least once. Those were crashes like yours that didn't happen.)
What I think happened is that the wiper blade got caught in your spokes and gave you enough of a jolt to knock your hands off and that your hands came off before any real damage was done to your bike. Better would have been to hang on for dear life and let your rear wheel destroy itself slowing you down. You might ultimately have gone down anyway but the wheel would have slowed you some and the crash would be a simple slide. Road rash and no broken bones probably, Now, if saving your bike was the number one objective, congratulations! You took the fall for your bike perfectly.
Ben, a big fan of letting the bike eat it for me.