Dear J.:
The bread/oatmeal/panko is always added so that the meatloaf doesn't come out as a meatbrick.
The egg is always added so that the loaf stays in one piece. Otherwise, the juices convert it to meatsauce.
The ketchup was just something your mom must have liked and, you're right, it sounds more like hamburgers than meatloaf.
You can probably come up with a better way to make it if you think about something similar which you probably like: meatballs.
I use super lean ground turkey or beef; vegetables such as fresh spinach, onions, finely chopped garlic, and carrots (finely chopped in the processor); spices such as pepper, salt, and oregano; and tomato paste and olive oil.
Yes, I add egg and oatmeal (rolled oats, not steel cut) because super lean meat is tough and needs to be softened with the oatmeal. The alternative is meat full of fat and you don't want that.
You can work out the recipe to your husband's taste but basically, it's good for both meatloaf AND meatballs. I can't give you exact proportions because I always cook different amounts and eyeball the whole thing. Close enough is close enough!
You can make both in the crockpot but the meatballs need to be seared first and served right away when they're done or else you get what we talked about before: a terrific meatsauce! It's probably more consistent to prepare in the oven so start there.
I wish you the best!
M.