1. It is easier to capitalize on people's fear and ignorance by using emotional key words like "assault weapon" to vaguely define whatever is unfamiliar to the zombified masses.
2. Someone on another forum mentioned that so called "assault weapons" are not as widely owned as other types of guns; so if you want to effectively seize people's property, you start with the minority, not the majority. Boiling frogs, and all that.
3. They've already succeeded with pushing an AWB before; so why fix what ain't broken? History tells them if it worked before, it will again. Then they can add to it and see what the people will let them get away with, rather than risk outright outrage and refusal.
Death by inches, if you know what I mean.