No I would not say it is cursed as I am sure you are not surprised I would say that.
However, America's climate makes it more prone to things like tornadoes than some countries, Canada doesn't suffer so much because it has a different climate. Same as the UK, but we do seem a lot more prone to rain. It's just like any where along the fault lines on any of the tectonic plates are more prone to earthquakes and in some instances, it can be on a pretty large scale. It's just the way the natural world works. Unfortunately tornadoes is one of those forms of weather than can be pretty destructive. We even get them in the UK, but for us, they are very minor, but our climate doesn't really suit a tornado well enough to give it the destructive power it needs.
But America isn't the only country to suffer from devastating climates, I mean, for many parts of Africa it means lack of crop growth due to the massive heat waves and lack of rain. Japan and many of the Islands East of Australia are prone to typhoons.
These aren't curses, it's simply down to climate.