Fun quote from an interview with Chris Sawyer:
Latterly the machine code came back to haunt us when the decision was made to re-launch the original game on mobile platforms as RollerCoaster Tycoon Classic a few years ago, and it took several years and a small team of programmers to re-write the entire game in C++. It actually took a lot longer to re-write the game in C++ than it took me to write the original machine code version 20 years earlier.
I think it's more so that the kind of people contributing to these projects are on balance not that interested in doing the marketing work.