C++ is a horrible language. It's made more horrible by the fact that a lot of substandard programmers use it...
In other words, the only way to do good, efficient, and system-level and portable C++ ends up to limit yourself to all the things that are basically available in C.
In general, I'd say that anybody who designs his kernel modules for C++ is either (a) looking for problems (b) a C++ bigot that can't see what he is writing is really just C anyway (c) was given an assignment in CS class to do so. Feel free to make up (d).
You can read the emails here.