Since 1998? Pfft I was using RAD in 1995 with Delphi 1! ;)
I've tried WPF and I'd love to say it works and I use it but It doesn't and neither do I. I've stuck with WinForms except where there is a requirement for WPF in the project. As you say WPF is clunky and feels like using a form designer from the 90s. But then a lot of .Net and Visual Studio feels like its still trying to catch up with Delphi 7.