Consider we generally do blood not lymph tests. That's a mix of practicality and tradition, but one one of many areas of basic research mostly left alone. Sure, doctors physically examine for enlarged lymph nodes, but that's because the immune system is largely based around the lymphatic system because that's mostly how diseases move around the body not through the blood.
Getting back to what I said, we can do a lot of high quality medical research that may or may not be useful in the long term, but we don't approach it as a research problem we approach it as an engineering problem looking for solutions to real world problems.
PS: As to CPU vs Medicine vs Physics. We are comparing numbers do large it's hardly meaningful, 10^20 (CPU) vs 10^30 (Medicine) vs infinity (Physics) all round to bigger than you can comprehend.
I'm not sure a researcher enjoys the same freedom to put together medical experiments as physicists and chemists do.
Moreover you comment sounds very disingenuous. It's like claiming that electronics is a realtively simple research domain because it still operates on well understood electromagnetics.
Meanwhile do keep in perspective that even today's state of the art in medicine involves various forms of mutilation.