They knew Fortran 77 and didn't want to learn Fortran 90+. I think they also had compatibility concerns. Unsure if there are any, though.
In over a decade in academia, I found only one person writing Fortran 90 (this was in 2001). He did it because he didn't tell his advisor he was doing it.
In over a decade in academia, I found only one person writing Fortran 90 (this was in 2001). He did it because he didn't tell his advisor he was doing it.