It's more so for the creative process. In my experience result is always better, more detailed when it has to go through progess and is built up. Rarely artist has "final image" in his mind when they start.

Sure, you could recreate this in GCI but it would be way harder to come up with the design in the first place.

I would also consider, any GCI artist could recreate this in 3D, but few could create it from scratch. If we consider that there was an good artist hired to do this piece, then it will be up to artist to choose his/her medium and you are critizing choice of artist or saying artist how to do his creative process and it is not about real vs GCI anymore.

Creating stuff from scratch is really really hard, it is always better to combine and build on things. The final product will look more original, detailed and overall better.

Art is messy, not optimized process.