This is "beauty is subjective therefore nothing is more beautiful than anything else" nonsense.
We can talk about expected beauty - that is, how beautiful you would expect a random person to say something is. And on that metric bare concrete scores very low.
> The Barbican Centre in London makes extensive use of bare concrete
It does not. Its concrete has been worked to expose the granite aggregate.
https://www.pinterest.co.uk/pin/255227503860482433/
Bare concrete looks like this:
https://www.friendlyshade.com/wp-content/uploads/2017/10/bar...
> and is widely appreciated.
It was voted London's ugliest building in 2003. And I would say it is appreciated more for its cool layout than its materials.