I'm not saying Benitez is a golden bullet and wont bring other problems, but he might well alter the culture behind the scenes and on the pitch - it seemed to form part of the input Abramovich gave - Martinez tried to an extent (play without fear), Koeman, Silva, Allardyce certainly didnt seem to, partially because they didnt stick around long (although Martinez from the first moment spoke of ambition, and achieved 5th and 70+ points - sadly he couldnt convince people to stay for the ride especially as things faltered) and partially they maybe didnt see it as their role.
As many point out the DoF should be a huge part of setting the culture, standards, expectations, and path of the club. For whatever reason, he isnt, or at least isnt in the eyes of the fans - we arent privvy to everything going on behind scenes, he may be doing more than we know, and indeed have his own hands tied at times.
Usmanovs nephew being around might just be work experience for the nephew, but I suspect there is more to it than that too. Still fascinates me how present he was in the photos of the unveiling of Benitez.