I train pre-teens in hogus as a general rule. There are times we do not, but again, it's the rule. As you, I teach control from day one also, but yes, I have found smaller ones take longer to learn control than most adults. (I have had adults that refuse to learn control but that's another topic.).Lastly, yes, I think child (pre-teen) students are certainly more fragile than their adult counterparts. I also believe children's parents are more fragile than the children themselves and appreciate seeing their children introduced to martial sport with protective gear. As for self defense, which is what my school primarily focuses on, whether children wear them or not depends on what they're learning. What I teach small children is very basic but effective as it has more to do with self protection than offensive strikes. They will learn what a strike feels like without a hogu, but they will receive a steady diet of it. Tolerance for receiving strikes needs to be built up over time. At what speed depends on the student. That's one of the advantages of a small school.
If you're experience differs, I'm not that surprised as my experience in teaching is in the low hundreds which I'm sure is considerably less than some here. Maybe over time my experience will teach me different.