Gonna state the obvious here (which sometimes doesn't feel that obvious I guess) : AC games differ from one another by the settings rather than anything else. That's a choice they made a long time ago and boys, you don't seem to realize how painful it can be to pull out a new full open world every year with a different setting (time + place). AC is a huge franchise which may or may not need a reboot cause people started to hate what made this series great in the first place (such as towers or tailing missions) which feels kinda akward too. Basically the "core gamers" expectations sums up to this gif when the mainstream audience seems to accept it pretty well for what it is.
http://i.imgur.com/pIvKZxD.gifv
I hate over anything else when people use the publisher name next to the words "make the game". People works on games, not companies names. Optimization, tailing missions or combat system that people enjoy trashtalking are the result of the work of programers, level design, animators and hundreds of persons. Do you think members of the game industry love to do shit and are happy to see hundreds of fans wanting for something different than they do ?
But take that and flip it - you have games that are made by thousands (!) of people, enough to take a half hour's worth of credit crawl to acknowledge completely.
And while the art team is still doing great work (muddy as it can be at times, Unity looks fantastic), and no doubt the other teams work around the clock to implement that year's given hook, the overwhelming feeling to people who have played each entry is "this is just more of the same."
Let's take tailing missions. Tailing missions might be bread and butter to the series, as you say, but they're not exactly fun, either. AC1 did these kind of well - you would follow a guy to an isolated area, and beat the crap out of him until he told you what you want to know. It was a decent diversion to get the information you needed to ID your target. Further games leaned way too heavily on this - I feel like AC2 maybe achieved a happy medium, where you would tail a target who would occasionally glance back. Unity took steps in the right direction, to get rid of the "listening ring" from AC3 and IV that caused instant-fail states should you step outside that arbitrary area. But AC3 and IV had so many of these missions that, yeah, absolutely, they should find a better way to accomplish the same story goals (half the time in 3 and IV, you couldn't even hear the details of what was being discussed, anyway).
Ubisoft sent out a survey earlier this summer that seemed to indicate that, yes,
they know. It felt targeted more at lapsed die-hards than ardent fans or newcomers. "Why didn't you preorder Syndicate?" "How do you feel about these mission types?" "Would you like to see more of this story or that?" "What can we change to bring you back in?"
It's clear that they feel they are, in some way, not delivering. And I think fans have every right, regardless of how much blood, sweat, and tears were pumped into each title, to have higher hopes for the series. Assassin's Creed 1 felt like an amazing proof of concept, muddled by some awkward tech and repetitive mission structure. With later entries in the series, we have games that are bigger, more open than ever, and nevertheless feel far more linear and guided than the original.
(To its credit, Unity felt like it tried pretty hard to right many of these wrongs. Even if you fucked up a tail or an eavesdrop, the game found a way for you to obtain the information you needed via alternate means. This led to a lot less repetition of missions that, in 3 and IV, would have been instant-fail, start from the beginning scenarios. Likewise, the "black box" or whatever they called it Assassination missions felt far better than 3 and Black Flag's "do these things this exact way to kill this guy the exact way we want you to."
And, given that, I hope Syndicate is every bit the Assassin's Creed 2 to Unity's AC1!)
I don't bitch about these games because I hate them, or the people who labor for years on them - I bitch about them because I love the older entries, love the franchise's potential, and I hate, year after year, to see it squandered. The so-called "Ubisoft game formula" is a real thing. It's certainly proven, and has repeatedly led to sales success. And for someone who plays a lot of Ubisoft games - it's tired.