[chungy]

Windows 3.1, 95, 98, Me all did exactly the thing described as "more trouble than it is worth"; they are 32-bit protected mode operating systems[0] that makes frequent context switches to 16-bit mode and utilize BIOS functions.

[0] Yes, I know, Windows 3.1 applications were almost always 16-bit unless you installed Win32S. It's somewhat complicated.

[smhenderson]

I guess in their case they had so much already written code to work with BIOS calls it was worth adding the shim layer. But if you were to start tomorrow with no legacy code then it would be more trouble than it's worth.

[chungy]

That is the story of Windows NT after all :)