So. When you use the accusative with motion, it is the same as "into". Where you use it with dative it = already located inside. Едем В Европу, на войну. Выйду на балкон... Etc all, literally, mean into, or onto. going into Europe, going (on)to war, stepping out onto the balcony. So, the "to" meaning is still sort of there, if that is the comparison you're looking for. However you won't always be able to translate 100% from any language to another language, so asking "Why isn't it like this?!" won't actually help you any. Its better to just accept things the way they are.

And Домой just means home, and you use it when you're going there. Я иду домой, они уехали домой, мама ждет меня домой к 10. Its the idea that you're going to your home.