They are a way of testing the waters.

They are a form of dog whistle to his knuckle-dragger followers. They provide him with plausible deniability ("I was obviously only making a joke"), And it lets his people know how he feels so it can legitimize THEIR blood fantasies as well as intimidate his critics. He knows he's doing it, we know he's doing it, his followers know he's doing it, his potential victims know he's doing it. And his partisans know he's doing it when they disguise their knowledge behind statements like; "It's just talk, if the media didn't make such a big deal out of it nobody would even have noticed it". We've heard that excuse right here on the zone. They clear their throat, bend down to tie their shoes, look the other way, pause to light a cigarette and pretend they didn't hear anything.

If he gets away with it, it becomes that much easier to do it again next time, only more so. If people protest in outrage, he backs off just enough (and distracts us with another broadside on a totally different subject). Trump knows his audience, and they cackle with glee at his lack of "political correctness".

Before long, we are fatigued with listening for his latest and everyone is tired of suffering outrage fatigue. We are inocculated to his poison by constant repetition, we build up a tolerance to it so it gradually becomes acceptable and objection to it can be dismissed as paranoid. This is precisely how Hitler worked.

I wonder what the 1920's German version of Godwin's Law was?