From what I can remember, HP's setting is the way that is is purely for a setting. The way it works has no deeper meaning than to make the setting seem magical and fantastical. While, all in all, Harry Potter's world is pretty basic and generic.

It just takes surface-level details of of old myths and witch folklore and just creates a setting out of it. They ride brooms, wear pointy hats and use wands. They brew potions in cauldrons. There are strange and sentient creatures in it because that's a hallmark of fantasy. All the while they're stuck in a medevil themed world because those elements fit better there. Except for the parts of the world that inexplicably don't, like the Ministry. And when you try to look any deeper at it, a lot of those elements don't mesh well with the "real" world of muggles.

I think Baby's First Fantasy Story could be an apt description of the series. But even then, there are other book series for children that have much more detailed and thought out fantasy worlds in them, so it's hardly an excuse. Especially when HP's plot just boils down Chosen One kills Dark Lord.

One thing I want to note is that for the house elves, those who are treated well, actively resist the concept of freedom. Perhaps this is simply the result of indoctrination, or given the magical setting they might very well be compelled by their very nature to be subservient and seek out a powerful master. I cannot recall if this is ever established.

Regardless, it brings to mind a Hitchhiker's Guide to the Galaxy animal, the Ameglian Major Cow. It is a sentient creature that has been bred not only for the express purpose of being eaten, but with the sentience and desire for such a fate, force-feeding itself just so it's tastier. Thus the question is posed; is it more humane to eat a non-sentient creature that by nature does not want to be and cannot consent to being eaten, or to eat a sentient and thinking being that does want to be consumed? If house elves want to be indentured servants, and do so of their own free will (presumably), then is Hermoine not impressing her own set incompatible of morals on them? But that's starting to get into Blue and Orange morality, and I think I've digressed enough as-is.