I think whether your chickens need to come in at night depends on your chickens and your local environment. Ours roosted in a dense tree when I was growing up. Despite a high predator population, we didn't really lose any to predation. Or cold, for that matter. They were wiley, half-feral barnyard mixes.
I keep mine in a coop now, because they haven't found a safe place to roost outside where we are now.
In Mexico, where my husband is from, all the chickens roost in trees for the night. Again, these chickens are practically wild and have access to primitive habitat to keep them safe.
For most chicken keepers in the US, I would recommend bringing them inside a coop at night. Even urban areas have high predator populations, since people don't hunt or trap anymore. And most landscaping, even with lots of trees, is too manicured and open for nighttime safety. And most varieties of chickens kept in the US have been domesticated past the ability to watch out for themselves.