I get it. But it seems like you are describing a puzzle action game. Combat shouldn't require enemy patterns to achieve depth. I'm not even sure you can count that as combat depth. I'd describe it as depth to overall gameplay. The great combat systems out there don't require specific enemy types to open up. It's an odd reliance for an action game.
There is no rule, or "should" when it comes to this, only the outcome.
the outcome here is a variety of enemy types that require specific attacks to take out efficiently (which is a staple action game design, in original and deep games too), a large variety of weapons, and a variety of mechanics mixed in such as counters, throws, dodges, takedowns, stuns, crowd control, beatdowns, evades, etc...
It has depth but it also allows you to ignore the depth, which is what many people do.
It has a lot of combat options that are tacked on after the fact and justified with gimmick enemies (more so in Arkham Knight it seems, haven't played it yet). This approach is inelegant, which means it increases depth in an "inefficient" manner, so to speak. This makes the system more complicated, but not more complex and barely more meaningful. This is represented well, at least in the previous games I've played, where once you resolved the occasional special enemy's built in defense, it returns to same very basic, highly automated formula that describes the game's core combat.
I get the feeling the "depth" you speak of is derived from the rather brainless scoring system, which is merely testing the player's ability to not mess up over a length of time (and this is/was alleviated greatly by the aforementioned dodge technique). That's basically the most creatively limited and unintelligent test you can put on a player. That such a scoring system would be necessary for a game to have depth is ass backwards. Ideally, the mechanics of the game would be naturally creative and testing in themselves, and the scoring system would exist merely to squeeze a little more out of it. Doing it backwards is like trying to squeeze blood out of a stone.
Again, the game is easy to learn and hard to master, especially hard if you learn every move available and make use of them often.
Play on New Game+ Hard (no counter signals and toughter encounters)
Play without taking a hit or losing your flow.
Take the enemies down in the most efficient time, ie: no constant "easy" dodging.
Make the most of your entire moveset, no repeated moves unless you exhaust them all.
Then tell me how automated it was.
If you play it mindless then yes, it will feel mindless.