If a country gets away with not having a mandatory military service, then it sholdn’t have one. Forcing people (usually just men) to spend a substancial amount of time in something, they might have zero motivation to, is unjust.
That being said, I absolutely support the fact that we do have a conscription based army here in Finland. There simply is an existential imperative for an army that is wastly larger than what could be achieved with volunteers. Maybe an initial fighting force could be mustered, but we would have problems refreshing it throug years of heavy attritional combat. Like Ukraine could most likely never maintain a fighting force through volunteer only.
That being said there is an option of civilian service here in Finland. I hold no grudge against anyone choosing that option. I agree that the system is fundamentally injust. I just see no alternative.
I watched similar thing happen in my own country. It was just one decision (so far) and made with a very comfortable parlamentary majority. The problem was that it was supposed to be unconstitutional according to wast majority of constitutional experts. That turned out to be absolutely no problem for the parlament and the administration.
It’s not even that I am too much against what they decided, but it did change my views on the nature of law. Any law or constitution is just a paper if it isnt enforced and will carry no weight, when it is simply ignored.