IMHO the big problem is new/delete, which C++ many programmers treat as close to 0-cost - in the kernel you have to worry about interrupts, SMP, real-time issue

IMHO the big problem is new/delete, which C++ many programmers treat as close to 0-cost - in the kernel you have to worry about interrupts, SMP, real-time issues and priority inversions caused having your code hang in ISRs trying to alloc memory - all that nice STL code, string code, etc etc it's full of new/deletes, it can't live in the kernel C programmers: you're not off the hook - malloc/free are just as bad, which is why the kernel has it's own context appropriate memory allocaters. And of course don't forget that malloc/free (and I assume new/delete) are not safe to be used inside user space signal handlers