Except in times of deepest peril for the nation, and no other means of obtaining sufficient manpower, the draft should not be considered. It is involuntary servitude and contrary to the principles of a free society.
That said, there is no reason not to require military service as a qualification for holding office, for federal employment, or even for the franchise. Limiting full citizenship to those who served, whether in the military or in civilian equivilents, is a good idea: those who are not prepared to contribute to society, and consequently have a serious stake in it, should not be permitted to decide important questions for that society. Think Starship Troopers!