Well, you're primary misunderstanding comes from assuming that they are telling you the truth when they talk about 'reasonable restrictions' and say that they don't want to ban guns. They are lying, plain and simple.
The fact of the matter is that their true goal is to remove firearms from civilian hands entirely. Period. Occasionally, when they accidentally tell the truth or think that no one who disagrees with them is listening, they say as much.
They realize that they can't get there in one fell swoop. So incremental-ism is the order of the day. Take whatever restrictions they can get. Ban individual guns, limit magazine size, increase cost through taxes and fees, etc. Keep chipping away little by little until they can reach their ultimate goal.
The last few years, this hasn't been working out for them. In fact, it's been going the other way with US chipping away at the restrictions, most notably with the increase in shall-issue CCW states and the mainstreaming of what they term 'assault weapons'. So they view the Sandy Hook incident as a godsend and a great opportunity to get their agenda back on track.