I'm in the same boat here with
@crowderjd for a few reasons. One being time. With a 3 year old and 1 year old I just don't have the time to polish legs, triangles, hardware, lid vents....you get the idea. If I have something that is more of a looker and it will be out of the cooking rotation for a long time I will razor scrape the lid and bowl, clean with Dawn and steel wool and put it away clean. I've recently been into sanding the handles and using Tung Oil to protect them and make them pop. Outside of all that, if the grill cooks, rolls across the patio with ease, and ins't falling apart I won't do the "full restore' on them.
Does it devalue the kettle? I'm not sure anyone can really answer that as my standard response is "a kettle is always worth what someone is willing to pay". I'm personally not going to pay more for one that has been painted because I'd rather see the character in the grill and leave it as it was found.
Same goes with my shaving gear. I and a traditional shaver with a mug and brush. I shave with vintage razors. I currently have some Gillette NEW long comb and short comb razors from both the 1920's and 1930's. I have not polished them and I probably won't. I like the patina and weathered look. I do clean them with a tooth brush and give them a soak in some Barbicide solution once I get them and periodically thereafter.
One exception to this would be if I found a flawless lid and bowl with shitty legs, wheels, and triangle then I'd spend time cleaning those parts up or paint them.