Point taken, and I can totally understand that. But when there is a choice of picking a word which is less frequent and one that is more frequent. It seems like the choice should fall towards the word that is more frequent, ie 里心 vs 里子.
That said, I don’t know at all why this particular word was chosen from the beginning. They might have a valid reason for it, or there might be a slightly more haphazard reason for that choice.