Of course, there is more than one reason why these changes came about and why further changes are being discussed (e.g. again abolishing the option of doing your residency on h1b).
One phenomenon I have seen in J1 docs is the fact that they are often from an urban upper middle class background in the country they where brought up. For them, working in some BF village in the rural US doesn't exactly offer loads of cultural stimulation. Many of the US docs working rural practices are themselves either farmkids or have some other attachment to rural areas (e.g. like to invest large amounts of money into equipment to kill fish, deer or ducks). For them, working in a rural practice is a lifestyle choice, and not a mandate brought upon them by the goverment.
And of course, there are the economics of it. Underserved areas are underserved for a reason. And as long as the medicare reimbursement formula punishes rural states and practice locations, and as long as medicaid pays such paltry sums for primary care, nothing is going to change about it. Rural and underserved by the way does not equal low income. In fields like family practice, a rural location is actually often an opportunity to make an above average income. Procedures such as sigmoidoscopy or c-section that are firmly in the hands of the respective specialists in most cities are often performed by FPs.
Still, I am somewhat disheartened by the attitude that I see by many of the guys and gals on this board whose primary interest is to find out when the first day is that they can get out of this j1prison. Now, considering some of the shady labor practices that particularly small practice (themselves usually FMG) employers use, this is no big suprise. But there are financially competitive jobs out there with benign employers, and still people can't seem to wait until they can get out of town.