The level of complexity of these systems is high even for today. But complexity has nothing to do with why we struggle today with vim, emacs, eclipse with gdb or what-have-you for developing and debugging.<p>Those who understand the system are few, and the time they have at their hands is scarce to begin even contemplating the amount of work required to develop a free alternative to genera.
I have no other explanation of why so many hobby projects started and failed at replicating what is still state of the art in programming environments.