C++ is old. It inherits most of C, which is also old. No other language has had to maintain backwards compatibility for roughly ~40 years, through generations of programming paradigms, while also trying to stay relevant. Modern C++ is a ton of new functionality mostly because its adding another paradigm to the language - since C++11 it has gotten much more functional.

Just look at how Python ended up if you want to see what happens when you try to backwards-break a language. And C++ is oh so much worse at that - if you make a non-compatible language iteration it would also (probably) break the ABI, which means "new" C++ cannot link old C++. It would make two languages. And nowadays, you really only have one of three reasons to write C++:

* You already have a C++ project.

* You need to use a C++ library / supporting code / integrate with C++ directly (and not through a C API).

* You want a feature only a C++ construct / library can provide. Qt is a great example of this, because there really is nothing comparable to it on any other platform in terms of a cross platform native UI toolkit, and using bindings can work but introduces a lot of build system complexities.

So C++ has all the reasons to adopt new paradigms to make life easier for those who have to use C++, but breaking backwards compatibility defeats all the core reasons you want to use the language. A prettier language is useless if you cannot get real work done in it.