There are all kinds of benefits to riding motorcycles, using power tools, cutting tools, and gardening equipment. There is no benefit to cleaning or lubricating your chain with the engine running in gear, and the risk is much higher than any of those things you mentioned.
My time is valuable. I used to spend 20-30 minutes carefully brushing my chain with WD-40, wiping it down, lubing it one section at a time. Now it takes me 30 seconds, and I'm more likely to lube it more often because it's such an easy task. Win-win!
Chain cleaning is a total waste of time.
I used to clean my chain every 500-600 miles... Now I do it roughly every 6-7K miles.
I see no difference at all. My chains & sprockets still last until 18-20K miles.
Agreed. If lubed often you don't need to clean chains at all. If you find your chain caked with sticky thick goo, find a new chain lube (like the one I posted above).

