to produce love for the Hive, or would the needed food gathering make it not worth it for the changelings?

So many reasons

• Constant influx of edible food for the foals in what amounts to a dangerous wasteland
• There's no entertainment in the Hive. It would have to be imported on a consistent basis and the changelings would have to make entertainment for the foals.
• You would have to emotionally manipulate them to love their buggy parents and siblings unconditionally.
• Accommodations like bathing/sanitation and medical care would have to be top priority.
• The foals grow up. He would have to have mates assigned to him to be his emotional caregiver for further manipulation.
• They would have to keep him entrapped within the Hive so that he could never escape.

Just podding a pony is the most efficient method. Taking care of a pony in the Hive under Chrysalis rule would be a nightmare and severe strain on resources.