I don't think most users of C want things changing underfoot.
Keeping track of all the version combinations is infeasible, especially when you consider that an app and its library packages are likely to have been developed and tested for a variety of environments. To the extent that existing correct code has to be scanned and revised when a new compiler release comes out, one of the primary goals of standardization has failed.
I disagree with your view of standardization - as restricting changes to be additions to the runtime seems pointless as users could easily use other (often more optimized) libraries.
But, I do see the benefit of having a language "frozen in time" which never really changes and can be mastered painlessly without having to refresh on new versions. Perhaps C is special/sacred in this regard.
