I’m surprised that you find that persuasive.
It suggests that humans are fungible: if some people die, it’s no matter, because more can simply be created. This strongly goes against my intuition.
I also think that human fungibility is flawed from a hedonistic quality of life perspective. Much, perhaps most, of human angst is due to involuntary death. There has been a lot of philosophic work on this. One famous book is Ernest Becker’s: https://en.wikipedia.org/wiki/The_Denial_of_Death/.
Involuntary death is one of the great harms of life. Decreasing the probability and inevitability of involuntary death seems to have the potential to dramatically improve the quality of human lives.
It is also not clear that future civilizations will want to create as many people as they can. It is quite plausible that the future civilizations will be reticent to do this. For one, those people have not consented to be born and the quality of their lives ay still be unpredictable. Whereas people who have opted for cryonics/biostasis are consenting to live longer lives.