CPUs expose a "mostly-C-abstract-machine-like" interface because this allows chip designers to change the internal workings of the processor to improve performance while maintaining compatibility with all of the existing software.
It has nothing to do with C, specifically, but with the fact that vast amounts of important software tend to be distributed in binary form. In a hypothetical world where everybody is using Gentoo, the tradeoffs would be different and CPUs would most likely expose many more micro-architectural details.
It has nothing to do with C, specifically, but with the fact that vast amounts of important software tend to be distributed in binary form. In a hypothetical world where everybody is using Gentoo, the tradeoffs would be different and CPUs would most likely expose many more micro-architectural details.