Why do people point to opensource as "copying" commercial software? Whatsup with that?

SOFTWARE (like MUSIC) copies itself endlessly.

Is opensource supposed to magically break the bonds of icons and menus?

Because opensource creates tools that have been needed on computers from the early days it is "derivative"?

There are categories of applications that both copy each other AND come to common conclusions about usage through practicality.

Is Gimp copying Photoshop (or Photoshop copying PhotonPaint or MacPaint) or just creating an image editing tool?

I think your premise is deeply flawed and only stands based on endless repetitions from handwringing webloggers. ;)

Look around and try to rethink your expectations of "innovation" vs practical solutions that are common across all platforms in the last 30 years.

After that try to look for the little things in opensource programs like "du -h" (as mentioned by newtechcity) vs commercial unix. Look again at the Gimp or Inkscape. Are you sure that they are only derivative? They bring many new things to the table but you're just not looking.