Yes, broiler chickens are a good thing. Good source of protein, quickly.
They kill the birds to stop the spread. A chicken that survives HPAI will shed the virus in poop for life. As the virus will only remain in the soil for a few months, it is better to remove the birds and start over.
In US, there are many indoor facilities for chickens. They are not always in cages, they can walk around (often), but kept under cover to minimize deaths/ illness. That is important when HPAI shows up (or other illnesses).
Eggs are important for eating and baking. But, also play a role in medical healthcare, snd research. Flu vaccines are grown up in eggs as an example. So, another important reason to protect the chickens and limit any HPAI spread.
Turkeys: Also susceptible. What exactly are we Americans supposed to eat come November ? Tofu turkey? No thanks! Protect the turkeys too!!