No, you don't. MDs make a big deal about taking histories and grading things by eye and such, but most don't really bother, aren't very good at it if they do, and, fortunately, it doesn't matter that much anyway. I have a colleague who looks quantitatively at the way physicians in a particular area use the standard scale to grade symptoms. Some do an okay job, but most are quite poor, and they're all highly variable. Various tests that are more automated or can be easily administered by a nurse (or student) perform much better.
On top of that, most physicians can't (or don't bother) to do the basic, simple math that's required to properly evaluate test results, either quantitative or qualitative ones, don't really learn anything new more than five years post-med school (which is still during residency for many of them!), make a frightening number of mistakes, and suffer from such blatant conflicts of interest that they're regularly made fun of on comedy shows.
I expect it will be illegal within 20 years to diagnose or prescribe without consulting an expert system. We'll have nurses, because people like the human touch, and computers. Surgeons will follow into obsolescence shortly after. The US will be a pioneer, as soon as the HMOs and insurance companies realize you can replace an expensive physician with a PC. When everyone realizes that cost cutting measure is also improving care, the rest of the world will follow.