You can beat any action game with standard combos as long as your defense is good enough.
Also, can we stop saying Ninja Gaiden had good A.I? Because it doesn't. It just has enemies with more frequent attack cycles. Which would not make sense in a DMC game considering there is no fucking block button. If you actually "LOOK" at the A.I being demonstrated by the enemies in the NG games, you'll see that it's just as dumb. They simply rotate around Ryu and have more frequent attack cycles and block more often. DMC would pretty much be broken as a game if the enemies behaved the same way.
Most people outside of our hardcore bubble (posters on a video game forum) within a bubble (hardcore devil may cry fans within a video game forum) probably do think like hypernima.
It's pretty shocking to know that most people can't wrap the heads around R1+direction stick back according to dante's relative position+/\ = hightime. From a general perspective, it's no wonder why Capcom opted to simplify the controls. It's the same reasoning why Capcom simplified the controls for Marvel vs. Capcom 3 from Marvel 2, what seems so easy for those already adept in competitive fighting games can't relate to the fact that the mechanics of these fighting games is simply too difficult for your average gamer.
I'm not even saying casual Wii-fit soccer mom gamer, but your regular joe. The kind of guy who couldn't get past Cerberus in DMC3, but probably still likely beat DMC1 on easy auto if you want to give him a classification.
Oh hell fucking no. This shit is on now.
You obviously don't know shit about the AI in the NG series, more specifically NG Black. The AI in that game runs circles around DMC, and not just because they block more often (btw that's a hallmark of good AI - aka not being cabbage heads) or have more attack cycles (oh shit really, you mean they don't stand around waiting to get killed?).
The AI actually reacts to what you do. Take for example the rocket launcher soldiers. If you've played the game, you'll notice that they don't actually shoot at you randomly. They wait for you to let your guard up or be in vulnerable frames to attack. Go a head and test it. Boot up NGB and hold the block button. They rarely shoot at you. Now do a wind roll. The minute you recover from the roll, they WILL shoot you. The minute you let go of the block button or move around, they will shoot you. If you jump, they won't shoot at you until you actually land again.
The soldiers in general will block all of your attack strings and punish you with a throw during recovery frames.
Cats will FS you more often if you try to abuse air combos.
Some enemies have moves to specifically counter yours.
Super purple fiends will do their underground teleport air combo attack as soon as ANY ENEMY guardbreaks you.
I could go on and on about how fucking awesome the enemy AI in NGB is. DMC's AI is complete garbage in comparison. Not even close. I understand your point about DMC kind of needing the enemies to be cabbage heads. It's true, otherwise you'd be constantly getting hit out of combos. But don't shit on NG's AI when you clearly don't know anything about it.