You just demonstrated another difference in C vs C++ mindset.
C doesn't need so many changes like C++, that is the fact and advantage. C++ introduces huge bunch of new stuff, you know add, add, add, then fix, fix, fix. At the end you get overengineered buerocratic 'give me my 5%' language.
So, in C99 some stuff are very useful like variable length arrays, restrict keywords, variadic macros... these are not cosmetic. And btw, evenfor that you don't need C99 to c89 converter, if you want c89 compatibility use macros. But, hey, macros are ugly, right? They are ugly but they don't make my eyes bleed as some stuff in C++.
So yes, i'm twisting your arm, sorry about that, but it needs to be twisted ;-)
P.S. Your compiler is your choice, just don't force others to use it.