Anyone who has tried to do cross-platform development knows it's extremely difficult in C++. You can do it, but it's not a trivial thing. I guess it's no surprise that Satoshi used Visual Studio. If you start out writing code in not-Visual-Studio, it's far harder to go back and make it run on VS.
I vividly remember how maligned Windows programmers were in 2008. I felt like a black sheep getting my start in the gamedev industry, because if you wanted to do Big League Programming in gamedev, that meant one thing: Windows. Microsoft has finally made some inroads in hacker culture. It's far less common now to be dismissed as less talented just because you used Windows. But in 2008 this feeling was very much alive.
https://sourceforge.net/p/bitcoin/mailman/message/23827020/
I used to be a Wine developer so it didn't put me off when I first found the project, but I'm sure the fact that it was Windows only hurt the projects uptake in the first year. It wasn't until Bitcoin 0.2 that a Linux version was available.
If it helps, Satoshi was also an Outlook user ;)
The bitcoin code looks and feels a lot like of their projects but could easily be some NSA programmers side project.
Any hacker can tell this was a one person project from looking at the code.
Fun fact: I was contacted by the Computer History Museum in Mountain View since this tarball (and the .rar) hosted on my site is the earliest known public copy of the source code.