Cool I see you point. But enemy AI...other than attacking what else where they supposed to do?
In any game built on diverse monster design you need variance in attack methods in order to make every encounter interesting. Take DMC1 for example, even in the most average encounter with Marionettes, the lowliest enemies in the game, they had multiple weapons they could switch to, their spinning lunge attack, their grab and their scream. At any time in any melee with them you could be subject to every attack variant simultaneously, so you had to cautiously mark and evade each attack while finding the precise moment to counter attack. It's because of this tactical diversity the enemies had (Which also expanded considerably on higher difficulties) that the game includes a File system for charting every enemy you encounter, with each nuance of their tactics being annotated when Dante experiences it, so if you're having trouble with a monster you could take a look at what Dante has observed in their behaviour and what his tactical advice is for dealing with it. You could go through the game multiple times and still fail to encounter every paragraph of a monster's entry, and it made for a fun challenge to discover them all.
DMC2's enemies are far more limited by comparison; while some might have a melee, jump or ranged attack to throw in occasionally there was far less nuance to each enemies behaviour. I'm actually happy to defend certain elements of DMC2's monster design, but the way they attack is a massive step-down from it's predecessor...like every other aspect of the game.
I'm gonna have to go through DMC2 again at some point(I have to anyway for an achievement) because you and another user pointed out the open arenas. I didn't catch them but any stage in particular that annoyed you with open arenas?
Most of the areas are extremely open, which is a baffling design decision. Consider the amount of open areas in DMC1: The zone around the coliseum, inside the coliseum, and inside Nightmare are the main ones that stand out. Generally open areas give the player too much space to work with, while claustrophobic ones limit how much you can dodge and give the camera the chance to emphasize both Dante's moves and the monsters. The opposite is in effect in DMC2, where the camera is absolutely miles away most of the time so it's harder to estimate Dante's melee range as well as pulling you out of the action. The only exceptions to the otherwise open environments in DMC2 will be a few corridors in the Catacombs and a handful of the industrial environments.