So the REAL leading character of SW is Palpatine?

[Moon Ronin]

Artoo didn't have a lot to do in TLJ and TROS.

You could have made a case for Artoo for the first 6 films and TFA (since Artoo having Luke's co-ordinates is important to the plot there).

TROS gives Palpatine primary agency. He created Snoke, he corrupted Kylo, subverted the New Republic and is the ancestor of the hero of the ST. This in addition to his role in the PT and OT.

The R2 thing is meant as a joke, having the same antagonist through out the franchise is not bad as having characters through out is not. Heck Chewy is the only one left for the originals maybe it's his story. No one was saying that the Middle Earth movies were about Sauron after he was wedged into the Hobbit trilogy. It was Luke and Leia that was smiling down on Rey at the end and not Sheev, though if they would have added Anakin and Ben Solo (or at lest Ben) it would have been the family was together at last.