This is a long time coming. There's a big backstory to it. Let me explain.
"Exie" was the codename for Microsoft's attempt to create, in Excel, a language similar to MATLAB (and later, Julia). The name "Exie" meant that it would be integrated with Excel. It was based on Alan Edelman's Interactive Supercomputing (ISC), which Microsoft acquired in late 2009 [0]. ISC's main product was Star-P, an auto-parallelizing compiler in which users used a *p suffix in an array dimension to indicate parallelism across that dimension, similar to CoArray Fortran.
Unfortunately, the ISC acquisition was a failure. Microsoft already had agreements with MathWorks and Cleve Moler (makers of MATLAB) which prohibited competitive software like Star-P. So Microsoft had to scramble and find other ways to get analytic, REPL, MATLAB-like software out the door. Unbeknownst to Microsoft, Julia was already making faster progress than they ever did, but on similar goals. Julia is what Microsoft had hoped Exie to become, and it's not a coincidence that Alan Edelman has been involved in Julia.
Then, Steve Ballmer decided to abandon HPC and mathematical software, and to focus mostly on the cloud, which led to the very public dismissal of Bob Muglia.
The head of Microsoft Technical Computing, Kyril Faenov, unfortunately committed suicide a year later. His wife, the daughter of a famous Seattle architect [1], did not respect his Jewish mother's wishes on the handling of his remains. His mother fought and lost in court [2].
Maybe Microsoft embracing Python in Excel is the best that can be hoped for now. It's certainly better than VB. But Exie tried, almost 10 years ago, to create an Excel environment closer to modern-day Julia than anything else.
There were a lot of personal sacrifices in that effort. For example, Bill Blake, the former CEO of ISC, stayed at MS for a while during the transition, then moved to Cray as CTO for a while, and then died unexpectedly less than 4 months after he joined D-Wave. [3] [4]
There's certainly been a lot of casualties, in the attempt to bring Excel up to being more analytically-friendly. Is it really worth it?
[0] https://blogs.technet.microsoft.com/windowsserver/2009/09/21...
[1] http://archive.seattleweekly.com/news/956673-129/seattleland...
[2] http://caselaw.findlaw.com/wa-court-of-appeals/1735359.html
[3] https://www.cray.com/blog/cray-ceo-reflects-on-bill-blakes-l...
[4] https://www.dwavesys.com/blog/2015/04/bill-blake