The main value of C is being the most compatible, well-known lowest common denominator. As soon as you add anything to it, it's no longer the C language, and yo

The main value of C is being the most compatible, well-known lowest common denominator. As soon as you add anything to it, it's no longer the C language, and you lose the benefit of universal compatibility and acceptance. This creates network effect in the C ecosystem that is so strong, that C99 is still "new", and C11 is an experimental curiosity. Anyone trying to improve C has to face the dilemma that being "C but better" doesn't seem to offer enough for C users to switch (you get all the headache of a "new" language for one or two features), and languages adding enough improvements to justify cost of switching have to evolve to the point of no longer looking like C.