Why I think about adding a kettle to my gear:

virtually unlimited fuel
virtually free fuel
fuel that can gathered rather than transported
efficient use of fuel
potential: not have to carry fuel bottles or cylinders, and spares, redundancy in any event

boiling purifies water directly and by generating steam for “stills”
water filtration will fail when its filters are used up or suffers mechanical breakdown
UV water sterilization system will fail when its batteries die
water treatment pills will run out
potential: not have to carry water filter system, spare filters, UV system, spare batteries, pills; redundancy in any event

much fresh, dried, and freeze-dried food and drink is “cooked” by just adding hot water
much cleaning and some wild-crafting is based on hot water
there isn't much other food that cannot be cooked on / in / around an open fire

I believe I can modify a kettle to securely carry water / tea / soup by adding a threaded cap
potential: not have to carry another water bottle

the “chimney” of a kettle can carry fire-starting gear and supplies
kettle setup inherently protects fire in harsh weather

Personal quirk: I usually carry a wide-mouth vacuum bottle or multiple layered freezer bags wrapped in some insulation used to carry slow-cooking food in liquid as I hike or journey to avoid having to sit around waiting at my next stop. Boiling water is by far the most frequent job I ask of my stoves.