And? "Unnatural" describes our entire existence - living in houses, eating food we raised, wearing clothes, taking medicines.
To be honest, 'nature' is that thing that constantly tries to kill us. I think its hilarious that folks pursue 'natural' foods and lifestyles, thinking its somehow better.
Birds nests and termite mounds. Ants invented farming and animal domestication (and slavery) before humans evolved as a species (certain strains of fungus have gone extinct in nature and only still remain because of their cultivation. Hermit crabs. And a few years ago (can't remember where at the moment) it was shown animals self-medicate when sick by instinctually eating certain plants they would otherwise not consume.
Those are all habits that developed organically over centuries based on our desire to live and lead happy, fulfilling lifestyles.
This is a brand-new procedure that just a couple years ago would be written about in a sci-fi novel. Perhaps you can understand how someone might think it's a little strange.
We have no clue as to how various chemicals released by the mother affect the newborn psychologically. Would probably not be able to predict the effects for over 10-20 years.
I'm worried we might end up with sociopathic kids. It's been shown in many animals that the mother does not bond with the newborn without oxytocin release from childbirth.
All the pro-life people i know that have seen it though think it's a disturbing, godless or unnatural...