Obvious, right? I don't mean they aren't persons, or individuals, or that they don't have feelings, or that I don't love them. I mean that they do not have human bodies, or human needs. They have horse needs, for horse bodies and minds that evolved in different circumstances than ours did.
I keep my horses beside a well-traveled road. That means the general public can see how they live and form opinions, and I'm sure many people would feel much happier to see my three wrapped up in cozy blankets.
But here's the deal. That's not what they evolved for. It's not what they need.
In a fascinating article on the Soul of a Horse blog, Natalja Aleksandrova discusses how horses' winter coats, and the fat they accumulate in the autumn, insulate them from cold. The ability of the hair to fluff up and stand out from the body, and the oil that prevents water from penetrating from the skin, can all be compromised by the tender loving care we give them. Blankets can flatten the coat. Grooming can remove the oils. A cozy winter stable can raise levels of ammonia (from urine, manure, and bedding) and cause lung problems.
So my horses stay unblanketed, with access to turnout 24/7. They generally go ungroomed from November until the hair starts to fly. I'll admit that I didn't know why these were good practices until today. They worked well for my horses for some 50 years, though, and now I know more about why.