They aren’t adding value to the Windows platform, unless you consider any application is adding value to the platform it is running on. In which case why should one pay for dev tools, their dev computer, libraries, art assets, etc…
Of course MS asked for it. They created and sustain this situation where software needs to signed for it to easily run on the Windows platform. Who do you think put the signature checking code and root keys in Windows?? The code signing gnomes?? fairies??
They didn't ask for ImageMagick. Would they have asked ImageMagick to develop the software for their platform to enrich it, I would have agreed that they should pay. Otherwise anyone can say I enrich your ecosystem so pay me.