my pov:
anyone who spends 10 years of their life (and most likely hundreds of thousands of pesos) deserves to spend the rest of their life using that training to achieve their personal goals. WITHOUT being second-guessed.
if people in the government or elsewhere are concerned about the 'brain drain', then they should pay for doctors' education. then they have a right to say where that training should be used. (btw, i know that there are already programs for this, but they're probably underfunded)
the people who "need the doctors the most" are their own families - their spouses and children. their responsibility is to take care of those people and give them the best possible life. while some doctors and their families will gladly forgo the riches in order to serve the less fortunate, this must always be an intensely personal decision...at wala na tayong paki doon.
finally, why are we singling out doctors? any businessperson or professional has the same capability to help their country and their fellow pinoys in a large way. an engineer can build schools, a lawyer can provide indigent legal assistance, a businessman can employ the homeless....are those people who leave the country (or choose not to do charitable work) also 'abandoning' it?