Geography isn't just climate. The US has exceptional soil for agriculture at incredible scales, one of the richest mineral belts in the world, and pervasive waterways outside of the Great Basin. Add to that just about every biome that exists within its borders.

Many people find Europe to be gloomy -- too little sun and too much rain. The US is only "harsh" if that is your platonic ideal for weather. The Pacific Northwest is a sunnier version of this climate. Most of the US is well within the range people can naturally adapt to and be comfortable in. The US is also an incredibly sunny place by comparison, even the parts not known for heat. The US does have unusually extreme weather but those events don't define the day-to-day and the built environment is adapted to it.

There are only a few parts of the US with irredeemable weather in my opinion. The low deserts of the southwest (e.g. Mojave) are literally among the hottest places on Earth. The northern Plains reach Arctic temperatures during winter. This is why almost no one lives in these places. The South famously has tropical heat/humidity during the summer, which Americans complain about, but that is like tropics everywhere and is quite pleasant during the winter.

That said, the best weather in the US (and arguably the world) is widely considered to be in San Diego. Perfect sunny days at an almost ideal temperature with no humidity for virtually the entire year.