Humans and dogs are not the same....at all. Anyway, i'm not saying that if the dog is clearly being an aggressor that its not okay to defend oneself...if you know how to properly do so, it would not include kicking the dog. But without that knowledge and working on instinct, sure i could see how one may kick a dog.
See, I look at it like this. If a human were to run up to me aggressively I would be reacting viscerally from the get-go. I'm not waiting to see how badly my children or I are going to be hurt before I start fighting back whether it's a person, a pet or a wild animal.