The problem with modern C++ is that there are several meanings of modern, and lots of classical libraries that aren't being rewritten.

I've never used modern C++, but I'd be interested to try it just to see what the overhead is in getting started writing some scientific code. When I was in grad school I used mostly Matlab, in which you can write matrix math without really having to learn any "programming". Same for numpy and Fortran. Definitely not for C. What about C++? Even the fact that pointers are being used at all would make it less attractive for a grad student who just wants to multiply some matrices.