You should be re-writing old code if you want to keep it conceptually clean, using the latest C++ standard.
What? No. One reason the C++ committee takes so bloody long is they put in astonishing effort to avoid breaking, or worse silently changing the meaning of, old code. In this regard, C++ is very, very stable.
You misunderstood me. The fact is, code is read by humans. Say I am a young programmer that starts working on a C++ project that has been growing for 15 years. How many different styles am I going to encounter? Do I need to understand them all to read the code? How long until I have seen it all and can call myself proficient? At what point do I re-write old code that I have to modify? How do I decide the re-write is necessary? (I know the same is true for C, but to a much lesser extent.)
2. For some problems, I prefer to have the complexity right in front of my eyes. In C, the code does all the talking
No you don't and no it doesn't. C abstracts plenty of stuff. Either through outright abstractions, such as implementing division and floating point for you on many platforms, dealing with stacks and function calls etc or via functions. Do you really know the inner workings of every function call?
If you really practiced what you preach, you'd write in ASM with on reference to external functions.
:) Don't pretend you don't know what I'm talking about. There is a balance between "explicit" and "abstract", of course. It just happens that C strikes the right balance for a job like systems programming, in my opinion.
I still think that C++ cannot be fully appreciated or used by people who would not be able to solve the same problems in C.
Well, that's quite possibly true. I was a long time C hacker before moving to C++. I generally understand C++ in terms of what it's doing under the hood. There are few mysteries. Much of what it does is the same sort of algorithmic code as C except it's vastly easier to write because it automates away the tedium.
Which is why I also think that C++ hate is generally misguided, and a knee-jerk reaction of die-hards.