The archaeologists know that and say as much in TFA:
"The paints used in the reconstructions are chemically similar to the trace pigments found on parts of the surface of the originals. However, those pigments formed the underlayer of a finished work to which they bear a very conjectural relationship. Imagine a modern historian trying to reconstruct the Mona Lisa on the basis of a few residual pigments here and there on a largely featureless canvas.
How confident could we be that the result accurately reproduces the original?
This point is not actually disputed by supporters of the reconstructions. For example, Cecilie Brøns, who leads a project on ancient polychromy at the Ny Carlsberg Glyptotek in Copenhagen, praises the reconstructions but notes that ‘reconstructions can be difficult to explain to the public – that these are not exact copies, that we can never know exactly how they looked’."
Contemporary historic preservation sees itself as the guardian of historical substance. The content of a monument is bound to the preservation of the inherited material.
Georg Dehio’s principle of "conserving, not restoring" is often invoked as a synonym for this self-conception. Old and new need to be clearly separated.
It is a counter-movement to the 18th century historicism which ”destroyed” a lot of old monuments beyond repair.
Personally, I think we went too far on the conservation angle (at least in Germany, not sure about other countries), and should restore a bit more again with the knowledge we have. But much more intelligent people have debated that for centuries, so I guess their answer would be the same like https://askastaffengineer.com/.
I'm in the conserving camp. It's more truthful than the narrativization that accompanies attempts to restore. We should remember that we all had a reptilian vision of dinosaurs for decades (centuries?) before the latest feathered view. We would have been better with neither. Just display the bones: what we have. Everything else burdens the public with guesses.
I mean, showing the texture of the underlying stone is how the vast majority of statues from classical antiquity are displayed, and indeed how most pastiches are created.
(and half the objection to the paint jobs comes from the fact we've come to incorrectly associate decorative elements from the classical period with the colours of bare stone)
Associating them with garishly and almost certainly inaccurately (based on pretty much all the indirect evidence we have) painted sculptures doesn't seem like much of an improvement, though?
I totally agree with. This is not a reconstruction because the shading, detail and subtler colors are completely left off. It's just a reconstruction of the statue as it would have been in an incomplete state!
"The paints used in the reconstructions are chemically similar to the trace pigments found on parts of the surface of the originals. However, those pigments formed the underlayer of a finished work to which they bear a very conjectural relationship. Imagine a modern historian trying to reconstruct the Mona Lisa on the basis of a few residual pigments here and there on a largely featureless canvas.
How confident could we be that the result accurately reproduces the original?
This point is not actually disputed by supporters of the reconstructions. For example, Cecilie Brøns, who leads a project on ancient polychromy at the Ny Carlsberg Glyptotek in Copenhagen, praises the reconstructions but notes that ‘reconstructions can be difficult to explain to the public – that these are not exact copies, that we can never know exactly how they looked’."