It is hard to teach old dogs new tricks.

http://www.stroustrup.com/slashdot_interview.html

) C++ for systems programming 
by ajs

C has long been the UNIX-world's systems programming language, and still remains that way. I know you don't like to compare languages, so I'll just ask if you feel that there are any core reasons why C++ either does not make a good systems programming language or failed to capture the interest of the systems C programmers.

Bjarne:

It is hard to teach old dogs new tricks.

Unix was first written 25+ years ago (I first tried it in 1973). All of its interfaces are defined in terms of C function calls, arrays, and structs. By the time C++ became available, there were 10+ years of tradition for almost exclusively using C.

There is no good reason for Unix programmers to avoid C++ and several good reasons to use it. However, there are no end of reasons/excuses offered. Let me list a few: