Microsoft wasn't exactly looking for a new format. They were looking for a way to pump data from the 3D app to the printer. I doubt anyone is going to be uploading 3MF files to Thingiverse.
While I actually like AMF (and the precision) the curved triangles give many people heartburn. The facetization might have been done with a data structure like STL but we all know there are way too many problems with that too. I don't know that Microsoft had much choice here.
BTW, this really doesn't affects us. Windows is trying to make 3DPrinting usable for the non-experts so that you can plug in a USB cable and then click "Print" in your software. While there is a mechanism to find out what options can be set from the 3D printer driver and the set them from you favorite design software, I expect most drivers and apps to only provide a few (print quality, color, % fill, etc). Most of the (advanced) people on this forum would still end up using a dedicated application (like Repetier Host).
SD2, glass bed, MK5 setup with E3D lite extruder
NX and Solid Edge CAD user
PI, Galileo, and arduino hacker
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