There is a much steeper learning curve for WPF, if all you are doing is a simple front end to a command line WinForms is a very easy way to get started.
Is this a scientifically supported assessment? I say this because I have heard it often, but in thinking about it, I cannot see this necessarily being true. WPF uses XAML, which is similar to HTML or other markup languages in structure. Sure, this is much different than the paradigm where you specify coordinates for all window elements (Win32, WinForms, et al.), but is it proven than a person having no background knowledge or experience in software would find markup-based layout more difficult than coordinate-based layout? Even if so, is the difference big enough to warrant telling all newcomers to use a coordinate-based layout, despite its inherent lack of responsiveness? Yes, XAML has many additional features, particularly in terms of effects, but these need not be used.