I agree with the statement regarding C and C++, it seems that backward compatibility is not a show stopper for them.
When comparing the evolution of C++ to Fortran, the rate at which new features are added is much higher in C++ than in Fortran. The drawback of that is feature creep and a complex language, exactly the opposite of what I love about Fortran.
Maybe I have to rephrase my point of view: I have absolutely no problems with developers who prefer old Fortran. I personally find it horrible, but there are many things that I find horrible but I have absolutely no problem if other people like it (for example German Schlager music). What I want to have is a more forward-directed language development of Fortran and I’m under the impression that his would be easier if one compromises on backward compatibility.
Apparently, writing a Fortran compiler is a difficult task (see my recent posts, ifort is wrong on DO CONCURRENT, gfortran on VOLATILE). It is not the first time that I report such bugs, I guess I have reported 10 compiler bugs in the last 10 years. This indicates the complexity required to write a Fortran compiler is already too high and I understand that vendors are reluctant to add new features. But new features are needed to keep Fortran competitive.
If the complexity is too high to be handled, reduction of complexity is a good solution. @certik already said that the complexity of obsolescent features is rather low, but it is still some complexity that for my purposes can be removed.