In fairness sir, this reality is only the case in the location where you happen to keep chickens. Chickens have many natural predators that are all habitat dependant. For example, the two predators you cite don't even exist in my location, but badgers, buzzards, and foxes do. A fox seems to be a very reasonable compromise owing to relative ubiquity and familiarity; the large range it occupies across continents.
In all fairness sir, the "natural predators" of a chicken don't exist anywhere outside of Southeast Asia (since we are being super technical); foxes aren't the ones that walk to the chickenwire barrier, reach through the wire, grab a hen around the throat, pull its head through the gaps in the chickenwire, gnaw off the hen's head, drink the blood that squirts out, and then release the hen and walk off. There are also minks, who will enter a coop through an inch gap, kill everything inside, rip it to shreds, consume nothing, then enter your house, open up all of your DVDs and put them in the wrong cases, put your toilet seats up, and leave for no particular reason. I also did say "nighttime" raids.