-Protection from elements
-Add gas, go, change oil occasionaly
-Tires replaced more often, chain replace, brake pads more often.
I wouldn't say motorcycle is cheaper.
I have 2 bikes and a car, if it is raining out. I am taking my car. If I am going to the store, I go in my car. If I just want to go down the block, I get in my car. Don't need to gear up.
If I want to have fun I take my bike, or go far on the freeway during traffic.