for next generation of medicine through research being integrated to the clinic, leading to be a leader in medicine. MD/PhD especially in top medical schools is very much rewarded both in money and career even though it will take 2-4 years in PhD phase.
https://students-residents.aamc.org/choosing-medical-career/careers-medical-research/#.Us1_h_X1YfU
https://www.sciencemag.org/careers/2013/10/finding-nirvana-paths-becoming-physician-scientist