If implementing an electronic health record is so expensive and burdensome for physicians, why is the Federal government so insistent that doctors do this?

The short answer is that the health care planners are misguided and blinded by their ideology; in the process, the computer industry has sold the government planners and some congressman a giant bill of goods; think "emperor's new suit of clothes".  Bureaucrats think only in terms of what might possibly help those who administrate the health care system as a macroeconomic entity rather than what might actually benefit the individual patient seeking medical care from the individual physician.  Electronic records may be beneficial for large medical clinics where doctors and nurses come and go each year like interchangeable parts and where the clinic is the permanent fixture acting as a repository of its patients' medical records.  In the solo physician's medical office or a group medical practice office, doctors and patients have a more stable relationship than that of a patient with clinic employed physicians.  The private doctor knows the patient, the patient knows the doctor, and both evolve together over the years of their doctor-patient relationship.