Yes we should have compulsory military service. It would keep a lot of the chicken hawks in Congress at bay from calling for another unnecessary war. Because many people would be enlisted compulsory service, any military action that is not warranted would be extremely unpopular. And these Senators and Representatives who voted for an unnecessary war would think twice.
If a person wants to support their country in a fighting way, they should be free to, but not forced to. Being forced to fight is like murder. Because if they refuse to kill, they are put up to the firing squad, and if they do kill, then they are being forced to. Nobody likes killing people, and nobody likes being forced to or be killed themselves.
To force others to go to war is paramount to dictatorship. No one should join the army or war because they have to. To serve in one's country is what one does from the heart because they want to do so. Not because a tyrannical government is gonna jail them if they don't.