Our ancestors fought for our freedom and we are slowly losing it. Everyone is slowly becoming more and more like eachother, shaming anyone unalike. How's that freedom? Millions of people lost their lives for us and we sit here being selfish saying "oh well there are better things to do" but are those better things stuffing your face full of food and yelling at their children to do their work. What would our ancestors think of this? Did they lose their lives for nothing?
Having a compulsory military service goes against freedom of choice, something western cultures stand by. Not only that, but people are needed in other fields and forcing them into the military damages those fields. A lot of people are fit for the military be it because they don't want to or because they wouldn't perform well, this would slow down any militant efforts.
I certainly would hate to be placed the environment the military creates and probably grow apathetic to my duties, costing the military a lot.