The ones dropped into the macerator are the lucky ones. The ones who live suffer for their short lives, until their economic utility curve crosses a threshold value and they are also slaughtered.
Reducing pain and suffering is better than not doing anything at all, and it's childish to assume that we can do anything more than regulate our food habits, and perhaps a couple of those around us. I'm vegan; I'm not deluded enough to think that my eating habits are anywhere near mainstream. There doesn't seem to be any end in sight for animal agriculture, whatever my personal feelings may be about that, so the next best thing one can do is reduce suffering where possible, and in-ovo sexing in hatcheries works a small way towards that.
Not getting to be born again (which by the way no one actually knows what that means) is different from not being born at all in the first place.
Of course the original premise is impossible, because no one knows how be unborn either.
If no one is willing to do something humanely, then no one deserves to have it. It's not a complicated analysis.
if those are the two choices, then i'd prefer the later.
but isn't there a third choice? to raise chicken in good conditions?
i suppose maybe that doing so would reduce the amount of chicken we can consume, and also raise the price, but i think that is preferable to letting them suffer.
While I get your overall point, I'd just like to point out the island of Kauai (and the rest of the islands of Hawaii). They have a massive wild chicken population.