In this case it's all about the look! Keyboards can also be made with a solid brass/stainless steel base, in which case it's about the weight which often affects feel, acoustics and overall "heft" of it as an object. Past a certain point, people make things out of cool materials/heavy just cause they can.

People break keyboards all the time. Reinforcing them with carbon fiber seems reasonable to me. You seem to be confusing carbon fiber, which is a mild irritant like fiberglass, with carbon nanotubes. It's goofy that the keyboard enthusiasts got taken in by the marketroid term “forged carbon”, though.

I have never once broken a keyboard. I can't imagine how I would -- sit on it? It's fixed on my desk.

If I did need a stronger keyboard, I'd rather have it reinforced with steel. That would have the extra benefit of keeping it in place.

Steel is a lot heavier and a lot weaker than carbon fiber. For you that's an advantage, but not for those of us who use our keyboards on trains, in cafés, in hostels, and in tents. The comforting weight of an IBM Type M keyboard gets old fast when it's stuffed in your backpack on a bike.

That probably also helps explain how we break keyboards.

Ah, okay. To me that's what my laptop keyboard is for, but I think I understand better now.

I used to travel with my mechanical keyboard a lot and the keyboard breaking while in a heavily stuffed backpack was definitely a big concern of mine.