This franchise creatively died when Ezio's arc was finished. It effectively died during Ezio's arc and entered repetition but attachment to Ezio made it worth seeing through. Once he was done everything since then has just been attempts at recapturing it but you just can't without introducing a fundamentally new edge to it. They had an opportunity to if they hadn't turned marx into a socdem they could've gone a cool as shit revolutionary through history direction bringing some much needed edginess to the purpose of thousands of years of assassinations but nah endorsing historical materialism is too edgy for corpos.

You could do something really cool with a revolutionaries through history idea but they're just not creatively willing to give to the political edginess it needs to have a cultural impact. Let me hang Mussolini upside down as one of Ezio's descendants and I guarantee you the game will be talked about literally everywhere.