To me, it's astonishing that you'd know someone as well as you claim to, and at the end of it all, they can't write a few paragraphs about you on their own. Like I said, I go to a significantly bigger school than you, and I've never heard of anyone having to do this, not even when asking professors that teach 200+ student classes. I will still say that writing your own letter is unethical and unfair because again, if she's really SO busy that she can't write you a letter, she's probably too busy to edit it a whole lot. The most any professor has asked of me is a resume and/or talking points for the letter (so, bringing up certain things I did in class that stood out from everyone else, for instance).
And my logic isn't flawed. Generally, if a professor can't write a few things about you, it's because they DON'T know you well enough, and if they are REALLY too busy to write you a letter, they tell you so. What do you really think that professor's going to talk about, you dancing with your girlfriend at a bar? There's a difference between a professor having some things in common with you, and a professor really getting to KNOW you. If in the course of knowing this professor for three years, through a class, and through research, they STILL can't come up with stuff to say on their own, then yes, there is a problem. The problem may or may be yours, but like many others have said on this thread, you would be better off going elsewhere for a letter.
I do hope you aren't this touchy in person...definitely doesn't show the compassionate, tolerant nature that is desired in medicine. I'm not trying to be annoying, as you claim; I'm trying to be helpful and honest.