Calling Win32 directly was already old fashion when Windows 95 came out in 1994, let alone 2005 when .NET was four years old.

The only folks already doing Win16 development with pure C code, instead of a C++ framework (OWL, MFC, VCL), VB or Delphi, were stuck in jurassic park.

The only valid reason for raw Win32 applications are games.