As with many (but not all) things Microsoft do, when the thick layers of gelatinous hivemind diatribe are pealed away what's left are sound, conscientious engineering decisions made by an organization with a near pristine history of supporting end users and going to extraordinary lengths to preserve backwards compatibility.

As for instances where they have not preserved support and compatibility, Silverlight comes to mind, and they dumped that largely in favour of frameworks targeting HTML+JS.

(I'm not a Microsoft employee, just a user who appreciates the APIs I cut my teeth on 20 years ago remain applicable today)

That's covered by the "backwards compatability" item.

It took them a while to even take patching security vulnerabilities in a timely manner seriously. I can understand that secure design (e.g. not running everything as admin) could fall under "backwards compatibility."

Yeah, I read that a few weeks ago, I can't remember the source. It will be really funny in the next year or two if the security experts encourage everyone to use IE to ensure a safe browsing experience.

You can be both! But I am usually more annoyed by rich content than the lack thereof. It grabs your CPU and memory and screams out to anyone in your vicinity, "Look what x is browsing!"

If I remember there is some issues with passing untrusted shader code to the GPU

So it may be a legitimate concern (only blown out of proportion)