I think you're confusing skeumorphism with decoration. Decoration is adding elements to design for the sake of aesthetic ornamentation. For example, Geocities websites had all kinds of blink tags and fireworks going on inside a webpage. That is decoration.

A save button icon that looks like a floppy disk is not decoration. It is a use of skeumorphic semiotics that takes advantage of historic familiarity - which is what you're referring to. I agree with you that it has its place in design. The original discussion of this thread is whether we should decorate websites with architectural motifs whether it is art-deco or brutalism.