I just exposed my opinion about why Microsoft made that move.
In my opinion they've seen the popularity of Arduino and though it was a good option to get more people used to Visual Studio. That way, when people will have to write softwares, their first thought will be .Net and the resulting software will be more or less impossible to port on other platforms. I never said that Visual Studio is bad in itself.
I think it's sad to use Visual Studio for µcontrollers. Especially when you already have so many open-source tools, libraries, etc. that are available for Linux, Mac and Windows to program AVR, PIC and many other µcontrollers. I'd rather use OS "agnostic" softwares for programming, especially µControllers.