OK,so what's this something special on the Pentax FF?

I think you are confusing words 'convenience' with photography in 'digital photography'.

LCD is not essential for digital photography, only sensor is. LCD can be quite distracting for many photographers. Quite a few of them still preferring to shoot film is not because they cannot live without film (more labs are disappearing each year, each year few emulsions disappear too), but because the philosophy of non-immediacy of results and the simplicity of film cameras allow them to focus on the subject, on premeditation and previsualisation.

It is about having less to experience more. In addition, cameras without an LCD can be sturdier, less fragile, lighter, thinner, more energy efficient.

Simply because you are not one of such photographers, you cannot deny the relevance of their ideas.

--
Zvonimir Tosic
“A portrait is not made in the camera, but on either side of it.”
— Edward Steichen