The kernel and the C library as a single project

Agreed! The original problem can be solved much better by improving the libc development, not by mashing it with the kernel. Maybe there could be some Linux-specific glibc fork that is updated very frequently to take advantage of the latest kernel features, but it must not be a part of the kernel in any sense, and must be replaceable by a totally different library if needed (this demands the kernel interface stays well-defined).