Why do architects charge for their TIME instead of their VALUE?

A client recently requested some quick conceptual design ideas to convert a plain boxy building into a Spanish style building.  I knew my father was the right architect for the task since he has 50 years of experience designing Spanish style buildings.  I, on the other hand, have only designed about 10 Spanish style buildings in my career, and guessed that it would take me about three times longer than it would take him.  My father whipped out a few sketches of each elevation in 15 minutes.  They looked great.  I let him know I’d show it to the client, and asked him how much he’d charge for the concepts (since he’s a subcontractor).  He said, “Well, let’s see, it took me about 15 minutes, so at my hourly rate of $200, that’ll be $50.”  I responded, “Well, that doesn’t seem right.  A surgeon doesn’t charge their patients for the amount of time it takes to complete a surgery.  A surgeon charges based on the type of surgery and his expertise, his years of experience, his know-how, and so should you!”  These sketches would have taken another architect many hours to complete, and they still wouldn’t have been as good.  Another architect would have charged hundreds, if not thousands of dollars for these.  My dad responded, “Well what do you think I should charge then?”  I decided, “Charge $300…..the client is getting an amazing deal and you’ll get 6 times more than you expected!”