As a software user and teacher, I think about software rot a lot. My concern is that it has a tendency to grow by addition rather than replacement. New features

As a software user and teacher, I think about software rot a lot. My concern is that it has a tendency to grow by addition rather than replacement. New features are added whilst the fundamental limits of the architecture are left unattended to. The reason that Blender grew from being an inside joke to a real contender is the painful re-factoring it underwent between 2009 and 2011. In contrast, I can feel the fact that the code in After Effects is now over 30 years old. Its native tracker is slow and ancient and not viable for anything but the most simple of tasks. Tracking was 'improved' by sub-contracting the task to a sub-licensed version of Mocha via a truly inelegant integration hack. There is so much to be said for throwing everything away and starting again, like Apple successfully did with OSX (and Steve Job did to his own career when he left Apple to start Next). However, I also remember how Blackberry tried something similar and in the process lost most of their voodoo.