We did not remove all non-netcore samples, only the ASP.NET ones, which represents only a small handful of samples. Most of our samples are multi-targeted (currently) to net7.0, net6.0, and net48. Our docs site engine splits these into separate single-framework downloadable zip files.
And really, they weren’t really “removed” either, but transitioned/rewritten to ASP.NET Core when the demand for that rose.
One big complication is that ASP.NET projects cannot use SDK-style .csproj files, which means they cannot be built with dotnet build, which complicates the entire toolchain.