Considering that we are talking about experimental toys which have lower odds of seeing production than of you winning a national lottery jackpot, the point of writing it in C would be the same as the point of writing it in anything else - IOW, the kernel is the objective, not the language used to write it.
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Yeah, but even if I'm doing something for fun I do want to be a bit unique with it. Anyone who's interested enough in osdev to build something for baremetal has at least attempted a unix-like kernel in C