I'm not quite sure which of the two you're suggesting we do now. They neither live in luxury nor their lifespan. Instead, they're basically tortured all their short life before we kill them.
If your ethical code is a variation of 'reducing pain and increasing pleasure for all sentient life' this would be orders of magnitude more good then the Peta option of turning them loose to die in the wild or never exist. It would be far more ethical than even artificial meat.
Heck from a strict cost/benefit analysis it may be one of the greatest moral triumphs mankind has ever given the universe.
Why would an industrial food processor care about how luxurious the sentient inventory finds the warehouse?