Do you not get sweaty on motorcycles? Even with a fully mesh jacket, I arrive everywhere _drenched_. In the height of the summer, I put on an athletic shirt and keep my real shirt in a bag to change into when I get to my destination.
If anything, I'd say bicycles are better because it's difficult to go fast enough to require the safety gear that a motorcycle does.
Disclaimer: new motorcyclist, used to race bicycles at a high level; I'm kind of a pedal head.