An open question independent of the author: What do people use Mathematica for that can't be done in R, SAS, Matlab, SPSS or Python libraries. Is it a great innovation that other tools have caught up with, or is it still getting a lot of use at the bleeding edge?
One thing people often miss talking about Mathematica is that the core math notebook features, 3d plotting, symbolic algebra tools have all been available since the early 1990s. Seriously, that's a long time, and a lot of user hours and development have gone into Mathematica. It's not perfect, it's not for everyone, I don't currently have a license, but to my mind, it's the gold standard for interactive notebook type…
late 1980s to be more precise…