I have never worked with this library but it seems to me that they have not the problems you described. Maybe having a look at it brings up some new ideas...
Although on superficial level it shares the AGOL/C-style syntax, Rust is a very different language from C++. Some things are possible or easier in Rust as opposed to C++ and vice-versa. Copying directly from a C++ library would be difficult, and wouldn't take advantage of Rust's unique strengths.
Okay. Thanks for the info. I just had a quick look at Rusts wikipedia entry and saw that it has been influenced by C++. But as you pointed out, this might not mean much...
Did you have a look at the Eigen library (C++)?
http://eigen.tuxfamily.org/dox/TutorialMatrixClass.html
I have never worked with this library but it seems to me that they have not the problems you described. Maybe having a look at it brings up some new ideas...