Excel is great at churning out fast and dirty estimates for low impact work. The problem is when it's used for large, complex, or important problems because these are just not Excel's domain--something obvious when looking at the kinds of features and bug fixes MS has prioritized over the years.
What this lets you do is in Python build networks of computations then change one value and it will cascade through the rest of your model, exactly like you do in Excel, but in actual code that can easily be versioned, reused, etc.
Yes, it's true Excel is used for a lot of big important things, but I'd agree with GP it's not very good at them. Moreover, I think most people who use Excel for big important things, would agree it's not good for it--they get stuck in that situation when a small spreadsheet grows big over the years. Lack of version control, limited modularity, and no ability to unit test make large spreadsheets error-prone, and Excel tends to barf on you when you push it too hard (seems to be a number of crash bugs and performance bugs that never get fixed).
Excel is incredibly productive for quick analysis and making charts. But it's really not a development platform and it's really not for heavy lifting.
The second big reason is that Excel just works, and all programming languages usually require installing tons of bullshit - editors, toolchains, whatever - to be able to work somewhat conveniently in them, and the moment any link in the bullshit chain crashes, you're SOL if you're not a developer. Yeah, we sometimes underestimate just how much minutiae knowledge we have that allows us to fix random problems in our tools without even thinking for a second about it.
So maybe Excel is unfit for purpose, but it's still the most fit for purpose tool available.
Based on the evolution of Excel, they clearly see it as a data analysis tool only, with lots of iterations of the pivot tables functionality. And clearly not as a modeling tool.
My guess on Excel usage is that it is 10% of the time used for data analysis (pivot tables, time series analysis), 20% of the time used to create a simple table (planning for the week by non technical people), and 70% of the time used for modelling (business plan, tax calculations, accounting, pricing financial instruments, running an inventory, calculating something scientific/mathematic, etc). Most companies are run on Excel.
For instance one thing where Excel sucks at one of its core functionalities is linking a powerpoint presentation to an Excel model. Any consultant, expert, banker, accountant, salesperson or marketer will do that all day. You can paste a table as a linked image but the formatting will be completely unstable and it is very dodgy. And no way to link a number in a textbox to Excel. Microsoft should focus on these problems rather than yet another pivot table functionality.
Though office seems to be frozen time. I can't think of any major new feature since Office 2007.
