gmab: Because the Torah gives guidelines for how to eat meat, and even gives vertain situations where a person MUST eat meat.
Shechita doesn’t have the animals suffering. It is the most humane way of killing an animal. Yes, I know you’ve said that the treatment of the animals up to that point is an issue. That may be, but that doesn’t make it assur to eat the animal. The treatment is a separate issue.
At the store where I buy my meat, they have a sign which goes through all the ways the cattle they use are treated humanely. No force feeding, no tiny pens, etc. Would you be ok with that?