I feel like you think you're talking to a different person than I am. My work computer is a linux box, my work IDE is either Jetbrains CLion or Pycharm, and my 40-hour-a-week-job is writing open source software that I release on behalf of Microsoft. So, yanno, if you want python libraries for graph spectral embeddings or approximate nearest neighbor algorithms, that's me.
The only thing I know about Visual Studio is it is distinctly not built for me, and I don't use it. I wouldn't know the first thing about creating a project in Visual Studio, because in the last 7 years I haven't created a single one in it. Gradle and Kotlin or SBT and Scala, sure. Python and pip, sure.
My problem with Python has nothing to do with the language itself. It has to do with the packaging. Remember that bit about me releasing open source software for Microsoft? Yeah. I'm stuck doing a lot of the packaging.
Friends don't let friends use Python, because then they're complicit in the frankly inhumane conditions in the pypa pit of eternal despair. Hug your numpy packager today!
I think it's easier and less risky to bank on a whole-ass isolated OS than it is to bank on making sure you have perfect coverage and mitigations in place for every possible module that ships with conda (not miniconda). But honestly, they could just require that Hyper-V is allowed if you want Python in Excel and offload it into a tiny little excel-hypervisor-daemon, same as they're doing in the cloud.
Ultimately, it's all just us reading tea leaves tho. I don't feel super strongly about any of the hypothetical motives talked about in this thread - not even my own. They're all possible, and reasonable people would make different decisions based on their priorities, and we don't even know what the priorities were of the team that decided to ship this. I mean, obviously they want to make money; but making money can be done by asking your customers to pony up more, or it can be done by having a strong degree of confidence that you won't get your ass handed to you when an xslx doesn't tap into cortana tts and try to extend your car's warranty or whatever. Maybe it's both. Maybe they want to start shipping Python with Windows but it isn't ready yet, so they're doing this Up There for a bit first. Or none of these. My goal in my initial response was just to say "it could be this too", in reference to the "there is no possible other explanation". There is a possible explanation. Heck, I gave you two new ones in this response alone! I only submit it as an entrant, not necessarily as the frontrunner.