What you describe is a valid reason for Windows to continue shipping with MSHTML.dll — not a valid reason to continue shipping the actual iexplore.exe GUI executable.

You might be surprised just how much legacy software does something like spawn("iexplore.exe").

And then there are all the internal corporate web portals that are still IE-only, and probably will remain so for as long as IE is supported in any shape or form.

Microsoft should certainly make it easy for corporate deployments to re-enable iexplore.exe — but it shouldn't be available by default on your typical Windows 10 install. (It's already available to uninstall and reinstall as an "optional feature".)

Or at the very least, Explorer and the task bar should do everything in its power to hide the existence of Internet Explorer 11. It shouldn't be listed as a program anywhere by default and it shouldn't come up in search.

So do something like what they did with .NET 2.0/3.0 where it’s a feature that has to be installed? But if it detects it’s needed, asks the user to install it right then? That’s actually a good idea. Why isn’t it like this?

This is probably a good idea. It seems that so many of the IE users I deal with at work do not need IE for any reason, they are just familiar with the icon and continue to use it even if any other browser would work just as well.

Legacy software like pretty much all of GOG's installers when you click the "Download" button on one of the embedded ads that show during installation :-P

Internet Explorer has a COM API which enterprise software (or worse, weird company-specific VBA scripts) can and likely does use to drive it directly. That API launches the actual iexplore.exe GUI executable and lets your code control it and interact with web pages, much like you might do with something like Selenium these days - except that this dates back to the nineties.