Its issue isn't being broken. But coming off of Arkham Asylum and Arkham City, games where I struggle to think of any low-point or game mechanic that wasn't implemented exactly how it should have been for the length of time it should have been, the Bat-Tank sticks out.
90% of what it is you've experienced by your third tank battle. From that point on it is pretty much more lines. "We'll throw more lines at the player, and that'll pretty much be the difficulty ramp". I can't think of a single time I knew a tank battle was upcoming and was excited for it. But with the predator sequences, dual-play, the detective stuff (outside of the side missions), most of the freeflow segments and most of the Batmobile chases I can say that I was looking forward to that experience. The Bat-Tank is just tedium itself. "Oh, another one of these sections, ugh".
You definitely do more of it in the main campaign that you do predator missions, chases or dual-play. It's a large part of the main campaign, and it becomes a more significant part as the game gets closer to the end. And the boss battles, dammit.
If they didn't have the Bat-Tank as a crutch I struggle to see how Arkham Knight wouldn't have been better designed. The best thing you can say about a game mechanic shouldn't be "Well, it isn't entirely terrible".