As part of being any type of physician, to keep board certified, you will be asked to continuously update your knowledge base. I think in general as physicians, we have an inherent love of learning and continuously seek to better ourselves and the practice of medicine by staying up to date in articles and evidence based medicine related to our field of practice
Short answer... no. To be a good doctor you need to specialize. If you enjoy children it's a great practice to be in. If you want to continually challenge yourself and learn more you should pick a specific field to practice in.