See, I rather enjoyed the rest of the game, indeed I was quite willing to say it was a savior of the series.
But then there were the last four story missions for Connor which were god awful, one of which was broken, how the final boss was killed, and Desmond's stuff, which, as a I say, what on the rest of the series.
It would only be worth it to see how badly they fucked it up, to be honest
As dumb as it sounds, you make a compelling case.
And if you weren't aware, AC3 was the last game by the guy who created the series before Ubisoft gave him the boot. That's why Desmond's storyline gets jettisoned for the most part, and why, with the exception of Black Flag, AC pretty much has been on a downward slop. (At least by my casual reading of the other game's reception.)
To me there was a lot more gold to mine after AC2. Like expanding the level of interaction in the cities. They went from none in AC1 (which to me is still kind of the most aesthetically evocative game of the series, and the best written), to generic upgrade-a-thon in 2, to slightly more interesting upgrade-a-thon in Brotherhood with the Estate and the Brotherhood and an attempt at multiplayer, to....some sort of weird hybrid action-strategy mini-game in Revelations? to.....crafting in AC3. Fuck. Loads. Of. Crafting. To boats and sailing in Black Flag. To...be honest I haven't really kept up with AC since that.
There are so many more ways they could leverage life and action within a city through your actions and behavior that they've never capitalized on. Like, remember when you're doing story events in 2 and Brotherhood and the layout of guards changes, the traffic density changes, hordes of guys might be there to fight or people might be hyper aware of you.....if Ubisoft would leverage that stuff dynamically as you play, in response to stuff you'd do, AC could become more like a sandbox and a hell of a lot more fun could be had in it. Instead they just keep tacking on more mini-games, more collectibles while the cities and the life blood of it just stay the game, adequate filler to make it all semi-believable and immersive.