They are extremely reliable and efficient during times of civil unrest. If a hurricane hit, or a tornado, or a California lingering rolling black-out, or some other man-made or natural disaster, you'd probably appreciat a neighbor with one of these guns. Or better yet, having one all to yourself in defense of your home and family.
That aside, it's an invalid question. In America, we don't have to show a need to own the things we want to own. Who needs a cars that travels faster than the speed limit, or an internet connection that is faster than 5 second web page rendering? Don't answer that, in America you don't have to rationalize it to me or anyone.
I'll ignore all the fundamental reasons (discussed on this and other threads) and give you a practical one that won't require you to understand constitutional law or political theories on freedom. Do you remember the riots in Los Angeles back in the early 1990s? Do you remember the Korean shop-keepers, who were able to protect their property and their lives (and the lives of their families and neighbors) against the looters with semi-auto rifles?
Those rifles are the ones being classified as "assault weapons" under this law. The law isn't banning machine guns (those were regulated in the early 1930s, and the only legal one ever used in a crime was owned by a police officer who would be immune to the restrictive regulations in any case, since such laws nearly alway exempt government agencies).
In addition, this law bans magazine capacities above 10 rounds. The result is that the Korean shop-keeper in the same situation wouldn't have the luxury of being able to fire "warning shots" like they did in that situation; they would have no choice but to shoot to kill or be murdered by the mob attacking them (and if the mob wasn't deterred, possibly both).
I realize that you probably don't have the time or the desire to do the research (but if you do, you can verify this information easily), but you should realize that according to the statistics these guns simply aren't used in crimes more than a tiny fraction of a percent (.26 of 1% according to the last FBI numbers I saw). In addition, they have the illusion of being dangerous to those that don't know any better, but the fact is that the intermediate cartridge they shoot is far less powerful (and less deadly) than the typical hunting rifle round.
In other words, just about all the arguments against them are based on lies; and lies are a bad foundation for public policy, even ignoring the Constitutional issues.
Like others have asked: "What is an Assault Weapon"?
Answer: ANYTHING the Government says it is. They could make a sling shot into an "assault weapon".
To illustrate how arbitrary the definition of assault weapons are the original Berreta 9mm handgun had a magazine capacity of 16 bullets. This gun was deemed to be an Assault Weapon under the legislation because of that. Oh, you can still buy that gun today or a Glock BUT the magazines now hold only 10 rounds. So, that extra 6-bullet magazine makes the VERY SAME PISTOL an Assault Weapon.
I have to wonder when the Feds will make any gun with more than a one round capacity ILLEGAL. This is all about SLOWLY eroding gun rights away over time.
Doesnt that mean you should know what an "assault weapon" actually is????
Because the government has them, and we heed the words of the Founding Fathers to forever fear and distrust the government -- any government.
There's the problem. Since "assault weapon" sounds bad, people that hear that on TV lean towards the left.
A lot of people confuse assault weapon with assault rifle. Assault Rifles are only legal with a Class III NFA. In some states, it's easy to get one, some it's harder or impossible, but they are legal in most states. Those fire full-auto and semi-auto. The amount of crimes in the past 50 years by those with Class III's. One, by a cop.
Assault WEAPONS are really no different than regular firearms. They LOOK mean and scary, but that's it. On another thread, 2 Civillian version(non full auto) AR-15 pictures were shown. One was legal. Another was an assault weapon. It was because of the grip or flash suppressor on the gun. The average person, and even myself could not tell the difference.
I call the Assault Weapons ban the Ugly Gun ban. MY definition of an assault weapon is any weapon that is used in an assault.