Why is it a bad idea to bill hourly?

Why is it a bad idea to bill hourly? How can you make more money and work less? How hourly billing limits the growth of your business. How hourly billing damages your relationships with clients. How does value pricing work? How does value pricing differs from hourly billing? How to start the transition from hourly billing to value pricing.

Never charge an overage again. Never justify your price.
@thefuturishere