Well, it's not surprising that his whole world revolves around Elise, considering she is the only person in his life after his father's death. He was abandoned by his mother, and De La Serre came off as a stern guardian, instead of a father figure, perhaps distancing himself because Arno was the son of an Assassin.

Him being very focused on avenging De La Serre's murder was because the only person he is attached to, directly implies that he is partly to blame for De La Serre's murder because he didn't deliver the letter. You can't blame him for clinging to that bond, instead of adopting a stoic life to deliver his comrades from tyranny and ensure freedom, equality and fraternity is achieved. He does eventually, after he is detached from all personal relations, and agrees to accept the life of an Assassin for the sake of people's liberty, based on the events of "Dead Kings", which takes place immediately after Elise' death, and long before his monologue at the end of the game.

Also, the revolution was everywhere. The story and co-op missions included a lot of events from the revolution, side missions introduced historical figures from the revolution, even the description of locations in the database talks about how the revolution affected those locations. Unless you mean it wasn't presented cinematically, instead of just excerpts of text in the database (with sassy interjections from Hastings), the game's backdrop was the revolution.