The continuation of the species is important we don't know where humanity will go and what it will face so genetic diversity is important to safegaurd against it in a macro sense, but i think if I were to make a case against it, i'd say

If you feel you couldn't provide for them or have no desire to take responsiblity for them, I suppose would be the primary reasoning, or maybe the country you're in would condemn them to a life you feel would be horrible

Monks, Priests and nuns don't have kids and that has been the case for many years, no one is saying that they are selfish, they just have chosen a different cause to devote their lives to and find meaning, and they also provide a service communities final valubale.