The basic science isn't to make you an expert in basic science. It give you a strong foundation to be able to pick up an article or textbook, learn what you need to learn, and then apply it. It's what makes a physician a physician; the foundation to learn and understand basic science principles and apply them to clinical management.
An MD is an undergraduate medical education. It's not about the facts and technical knowledge as much as it is about a strong foundation to learn and apply basic and clinical science. It's more about the medical method of thinking and problem solving than the actual knowledge. As in every other field, the detailed technical aspects are learned in graduate education.
I never understand why people complain about "useless" basic science. You may not use those specific details, just as a BioChem PhD probably nevers uses 90% of the biochem they learned because it's irrelevant to their specific niche. But if you strip away that foundation and understanding and you strip away a large portion of what makes a physician a physician...