A reason to learn Fortran besides the ability to write stand-alone programs is the ability to extend other languages or programs with a function or subroutine. This is often done to extend general-purpose languages such as Python, R, and Matlab. At GitHub I see a number of projects that extend specialized codes such as Abaqus and LS-Dyna. What are some others? A web page at Fortran-lang could list such programs and explain that even a modest proficiency in Fortran can enable you to attack difficult problems.
FORGE is a FEM software for material forming simulations. Users can extend its functionalities with Fortran user-routines >> Generate its own user routines in FORGE®