There is nothing wrong with any of the primary care specialties. The nation's health policies have always driven primary care choice and distribution. Not having Distributional Health Policy is a problem for the 70% of the nation that need health care.
Funding for clinical services, graduate medical education, research funding, public health funding, and supplemental hospital funding all favor major medical center and medical school location. Primary care outside of major medical centers gets declining Medicaid and Medicare and insurance, the lowest levels of reimbursement, crippling regulation, inability to negotiate based on low numbers of patients and providers, reduced patient care revenues (co-pays, urgent care, ER use, barriers of transportation and day care), and increasing costs in liability, salaries, utilities, rent, and numerous areas.
Subspecialties Flourish as Internal Medicine Graduates Shun Primary Care
Position Paper Redesigning Internal Medicine Annals of Internal Medicine
Garibaldi RA, Popkave C, Bylsma W. Career plans for trainees in internal medicine residency programs. Acad Med. 2005;80:507–12. Full text article
The Collapse of Primary Care - Rosenblatt
Changes in Specialty Choice 1987 - 1999
Office Based Proportions in IM, FP, Pediatrics
Five Periods of Health Policy and Physician Career Choice
The Advanced Medical Home: A Patient-Centered, Physician-Guided Model of Health Care
Your Future is Family Medicine Talking Points