I actually used raw GDI+ for the GUI of an app recently. My personal requirement was that the executable had to be completely stand-alone and only a few KB in size. GDI+ helped fit the bill for creating a simple GUI and eliminating dependencies on large frameworks, so that it could easily be copied around and guaranteed to work everywhere.

Wouldn't use raw GDI+ for any UI of moderate complexity, but it was perfect for the ghetto app I made myself.

Windows Remote desktop (display redirection) used a GDI xpddm driver up till Windows 19h1 (and Windows Server 2022). They switched to IddCx which is pretty cool to play with.

Even in C#, the default image handling libraries use GDI+ still, even in .NET 7. There was some sort of attempt to make it work on Linux (via some sort of shim or comparability layer, I assume) but MS abandoned those efforts after .NET Core 3.1

Yes, it is much easier to use than Direct2D.