I've never seen anyone use Mathematica outside of academia other than myself. It also occupies a slightly unique corner of the language design landscape. One that I like!

I wish that Mathematica was modernised and made into a proper, compiled (or at least JIT-ed), heavyweight language with all the trimmings. A proper IDE, debugger, tracing tools, etc... The current version is a bit like Visual Basic -- a very old language that had grown past its original design capabilities and now needs a revamp. A bit like how VB.NET replaced VB, and was superseded in practice by C# on dotnet core.