A draft is good for establishing a sizeable reserve of moderately trained personnel. A professional/volunteer force can normally be trained to high levels.
What I think it boils down to is what is most useful for the military defence of your country. If the security challenges you face call for a big reserve, a draft is a good option. If you are best served with a high-tech force requiring extensive training, volunteers may be better. Domestic politics and social engineering are very much secondary considerations in my opinion, and best kept as separate as possible from the running of military affairs. The more non-military aspects you saddle the armed forces with, the more you run the risk of ending up with a watered-down compromise military that doesn't fully satisfy any of the requirements.
Or at least those are my initial impressions on the matter.
Mandatory military service is a good way to weaken your modern military. Firstly, morale is terrible. Apart from the volunteer professional military people, no one in my company wanted to be there. No one. Everyone saw their military service as something to be endured, something to get over with. Psychological problems were common, including a few suicidal individuals. Discipline was as lax as they could get away with, because running a tighter ship would likely have caused even lower morale.
All the while it does up the numbers while maintaining reasonable costs. Which solution is better depends on the threat environment, I think.
I must say that my own experience with the finnish conscript military was not quite so bad as yours. Of the conscripts, there were a few people who liked being there, and a few who had significant problems with military life, but the attitude of most of the rest was pretty neutral and something akin to "well, we're here, so let's just get on with it". I personally found discipline and morale to be more of a factor of the leadership qualities of both the professional and conscript military leaders.
Secondly, the quality of the soldiers was pretty poor too. You've got guys who just graduated from university, guys who have spent the last four years sitting on their butts playing the latest Blizzard release. These guys can't do two pushups without cramping up, they can't run for more than five minutes without puking. They think firing a gun is like something out of Counterstrike, so not only can't they shoot straight, they're also so startled by how loud actual guns are, some of them actually started hyperventilating.
That's the thing with universal conscription, the troops start off being just as fit and well-adjusted to military life as the average young man on the street. Though I don't remember any truly hopeless cases; those probably went the conscientious objector route.
Thirdly, it doesn't really help with the disconnect between civilians and the military. All you've done is create a disconnect between the "voluntary" forces and the "involuntary" forces. To maintain Taiwan's military strength, the parts of the armed forces most likely to see combat are manned almost entirely by volunteer career troops. This means the majority of combat roles in the navy and air force are volunteers. The parts of the marine corps most likely to see combat are also mostly volunteers, if I'm not mistaken. This means the conscripts are mostly sent to the army, or non-combat roles in the navy and air force.
I'm not sure I entirely agree with that. Some 80% of finnish men have done their military service, which is one of the few things that they have in common. Whether you are a private or a general, you crawled through the same mud in boot camp, and everybody's neck is on the line if shit gets real. While I imagine the communal spirit is not quite what it may be in more exclusive clubs like the US Marines, I think it still exists, and regardless I believe the time spent in the military does give the conscript a greater understanding of and stake in military affairs.
If there is a gulf between the military and civilian populations in the US, I think it'd be a good idea to try to bridge it. But I highly doubt a draft is the right way to do it.
I agree entirely. If the draft is re-insituted, it should be done for military reasons, not socio-political ones.