Earlier quoted context omitted.
> Replacing unsandboxed plugin APIs like NPAPI that can directly access the OS with sandboxed plugin systems like NaCl and emscripten that support sandboxed native code seems like a major improvement. Until you want to write a plugin with a legitimate reason to directly access the OS.
Legitimate reasons to directly access the OS are typically "there isn't a browser API for this yet". We have multiple Open Source browsers now; submit a patch to one or more of them to add a new API, and ideally start working to standardize it. The result will be far better and more secure than a one-off custom plugin to pass through specific OS functionality.
Web standards and the web standardization process are broken.
An example is webrtc, which was practically designed for webcam chat, yet this is still completely broken in a cross platform/browser context years after the fact.