I ate horsemeat as a child, which means I've already thought about this. I think it's more respectful to eat what you kill, and it's clear that since we do have herds of wild horses, they will have to be killed sometimes (their populations can't be regulated by natural forces).

I remember my father telling me that the prohibition against eating horse derives from attempts to drive out pre-Christian European religions, among whom the horse was a holy creature whose consumption was connected to various celebrations. He said that you could see where the holiness of horses and the ritual eating of horses had been by seeing where modern people are disgusted by the idea of eating them.

For myself, I won't eat primates, and I won't eat marine mammals,because the former are my family and the latter are family by adoption. There are other things I don't eat because I don't have the taste for them (most invertebrates). Somewhere I picked up the way to say it: "I do not know how to eat this thing." But marine mammals and primates, I refuse to learn how to eat them under any but the most dire circumstances.