>Probably because most users of excel don't have any experience installing and running Python which is even a pain in the ass for people that know Python lol.

An embedded Python is about 10 MiB. I just checked. Excel could easily have its own separate copy.

But don't you need to install lot of packages for it to be useful?

Based on the announcement it looks like the standard data-science libraries (numpy, pandas, matplotlib, seaborne) will be available. The covers a lot of use cases. However I would really appreciate the ability to set the python interpreter to whatever I want. Then I could access the niche libraries I need (shout-out to JSBSim for open source flight dynamic modelling). Or even better, hooking up my organizations custom libraries we built for our own specific data analysis applications. Huge value add. Shame this likely won't be possible. Unless I've misunderstood some part of this.