It's about responsibility. Democrats belive the state has a reponsibility to take care of every aspect of your life, including your protection.
God forbid should you have a gun and be able to protect your own life or that of your family. To the Democrats (the statists), that is the responsibility of the state.
And that after this is accomplished, and the brave new world begins
When all men are paid for existing and no man must pay for his sins,
As surely as Water will wet us, as surely as Fire will burn,
The Gods of the Copybook Headings with terror and slaughter return!
- Rudyard Kipling, 1919