NEW COMMENT: I really screwed up below in describing the Australian hostage situation. I didn't realize when I wrote my comments that the hostage taker WAS killed; I don't recall whether some of the hostages were, too.
OTOH, it's absurd to think that hostage-taking situations like this end any more peacefully in the US, whether they occur in states that permit open carrying of guns or in states that ban it. In Blacksburg, Va. in 2005, I think it was, at Virginia Commonwealth University, a crazy and angry student bought handguns at a nearby gun show and shot something like 32 people, killing many of them. The fact that Virginia allows its residents to own handguns did NOTHING to prevent the massacre.
Similarly with the shooting in the movie theater in Aurora, CO a few years ago. Colorado law allows people to own handguns, I believe -- and yet when James Holmes opened fire in the theater, nobody stopped him. It's just not accurate or plausible to say that the Australian hostage event would have ended differently "if only" the Aussies got rid of their gun laws.
Original answer:
I'm not for banning ALL guns. My dad was a proud duck hunter, and loved his hunting rifle and his shotgun. I think Americans should have a right to own hunting rifles & shotguns, at least Americans in rural areas.
Here in the big city -- I live in Washington, DC -- I think even hunting rifles and shotguns probably need to be banned. Back in 1991, a crazy guy drove through my neighborhood shooting people at random with a shotgun, and killed 4 or 5 people this way for no good reason. If there is some way to prevent this via restrictions on gun ownership in urban areas, I might support it.
I also think maybe we should ban all handguns, especially handguns in cities. There are probably 10 or more people I know who've been killed by handguns in my neighborhood since the 1980s, some of them in drug trade-style executions, two or three in armed street robberies, and one who was killed by someone holding up a convenience store.
I think the US could reduce this kind of crime while still upholding the spirit of the Second Amendment if we banned all handgun ownership or at least all carrying of handguns in cities. Many frontier towns in the Wild West actually did ban the carrying of handguns inside city limits in the 1880s, and somehow the Constitution survived. I think we should think about imitating them.
THIS IS WRONG, WHAT I WROTE HERE -- Sorry about that. I'm embarrassed I blew this part of my answer so badly:
*** As for the Australian hostage situation -- didn't this one end with the police capturing the guy, without killing anyone? **
Contrast that with the all-too-common pattern here in the USA, where hostage situations often end with the police shooting & killing the hostage taker, and many of the hostages getting killed in the process.
OTOH, gun control in the US is a LOST CAUSE, because of the strength of the gun lobby and the NRA. Every time a mass shooting occurs, the gun lobby & NRA flood their supporters with dire warnings about the government supposedly being ready to confiscate "all guns." Then, sales of handguns & rifles usually increase, as paranoid gun owners rush to the stores to buy more weapons before the threatened federal crackdown occurs.
In other words, calls for "gun control" in the US usually succeed only in increasing gun industry sales.
I think Americans just need to get used to living in a savage & violent society, because nothing much can be done about this.
BUT -- Maybe the nation's proud gun owners will decline in numbers over time, partly as a result of rightwing gun nuts turning to their weapons in family disputes, so that armed husbands & wives end up killing one another & reducing the gun-owning population.