I know very well that our ancestors ate meat for a long time without cooking it and I'm of course not saying that was a huge problem. Just pointing out that parasites
can be a huge problem and a strategy which reduces the parasitic load should be adaptive. Even regular pork tapeworms can kill people! I'm not saying it's the primary factor which makes cooking adaptive, just an interesting piece of curiosa.
As for the viability of factory-grown food, why do you think it would be so expensive? We are imagining the use of a technology not yet invented after all
I'd imagine if you had a hunk, or maybe a flat sheet of meat to increase surface to volume ratio, growing in or on a medium almost like a lump of cancer, you would not as much have to worry about things like space, sex, health, transportation of animals and you could likely grow it more effectively using less energy per pound meat than what is produced by real cows and pigs!
edit :
I have a sneaky feeling we may have gone through this before in this thread.