Do you have any evidence to suggest that those deaths would not have occurred if guns weren't available? Looking at countries that have very strict gun laws, it looks like they still have issues with rampage killers. It it possible to kill someone with something other than a gun, and when guns aren't available people just find another way to accomplish the same thing. The one that particularly stands out to me is the guy in China who entered a school, doused a kindergarten class in gasoline, and set them on fire. Someone intent on killing a room full of kindergartners is going to figure out how to do it, and no amount of legislation is going to stop them.
Gun deaths per day include suicides. Banning guns would just cause them to kill themselves by some other means. Remove guns and you'll only shift the statistics from "suicide by gun" to the other "suicide by ____" buckets. In the end, you haven't accomplished a thing.
Almost half (49%) of all homicides using firearms are inner-city kids killing one another. I can guarantee that all of the firearms were obtained illegally, because it is not legal to sell to a minor. We're talking around 5,000 children killed per year, and I haven't heard of any proposals that do anything about that. The issue there is not "assault weapons" as those are almost all handgun deaths. Nor is the issue "high capacity" magazines. What is the underlying cause for thousands of kids per year to feel the need to try to kill one another? Focusing on the why could help eliminate so many deaths per year. Tons of existing laws are being broken -- seems like there's plenty of room to "do something" with the laws that are already on the books, although again I think only addressing the method used for killing would simply see a shift from guns to knives, or some other weapon.
What TFA points out is the futility of a renewed ban on high capacity magazines. Technology has improved to the point where anyone could "print" their own. The genie is out of the bottle. There now is no way for a law to keep high capacity magazines out of the hands of people willing to break the law. Perhaps in 1994 when the first AWB went into effect it could have been possible (didn't matter since existing magazines were grandfathered, and there were plenty of them on the market). At this point a law banning high capacity magazines would make people "feel" more secure, without actually making people more secure.
Also, not to be too pedantic, but it wasn't an "assault rifle" . Assault rifles (shoulder fired firearms capable of select fire (more than one bullet per pull of the trigger)) are already banned, per the National Firearms Act update in 1986. It also was not an "assault weapon" as those are illegal in Connecticut (using the same definition of "assault weapon" as the 1994 AWB), and it has been confirmed that the AR-15 used in the shooting was a legal configuration in Connecticut. A huge part of the problem in the whole gun control debate is people not really understanding what it is they are talking about banning. The details don't matter for those who would just like to see all guns banned, but for everyone else the details do matter.
"WTF, how can you possibly claim it wasn't an assault weapon?" I anticipate many are thinking. Easy. I've read the law. To be an assault weapon, it must be a semi-automatic firearm that accepts a detachable magazine (check), plus has two of the following features: pistol grip (check), collapsible stock, bayonet lug, flash suppressor. The CT gun didn't have a collapsible stock, bayonet lug or flash suppressor, so it wasn't an assault weapon. At the end of the day, "assault weapons" are just guns that have certain cosmetic features -- they don't function any differently than semi-automatic guns that aren't "assault weapons." They aren't more lethal.
Feinstein's new proposed Assault Weapon Ban is similar to the 1994 ban, but change the "two" to "one" for the features. Every pistol has a pistol grip, so all semi-automatic pistols (most non-revolvers) would become "assault weapons." She then has a list of guns that are exempt from the overly-broad new definition of "assault weapon." And therein lies the problem with banning "assault weapons" -- it's a made up category that isn't easily defined.