They wanted to embody one half of everything that was wrong with Western action games OP. By meshing the over-simple 3D action combat of PS1 3D action games with the modern press X to awesome (and win) slogfest with a simple skinner box system of minor and numbing dopamine injections with pop-up numbers that delude you into thinking you're doing something meaningful and thought-heavy.
In order to revamp the original system and give it some substance, I want to take you back to 2007 when I first played the original game. I remember feeling like I had wasted some time and missed some things I could have and should have gotten early on when I played it on the PS3 back in 2007. I had taken what I already knew and paid closer attention to everything going on in the game and had the combat system spelled out to me clear as day at the beginning of my second new game. The game tells you outright, press the square button when you see an enemy preparing to strike. You rhythmically tap the button and ultimately the enemy dies. Only one enemy will engage with you at the time (something ubisoft addressed shallowly) and this is how combat works until you get the counter insta-kill.
The problem is that there's a lot of work put into making it look cool, never testing your understanding or limits and rigidly pushes you to engage in the easiest kills possible as the game hits peak tedium if you fail to. They didn't want to give the enemies tells, the player a move set to engage with and anticipate the enemy behavior. In order to balance that feels realistic and looks cool style it has they couldn't make a game that plays well. The thing is, I don't believe they were capable of doing even that if you look at their previous games. It's all too much work to study how the Japanese succeeded in a variety of combat systems and figure out your own failings when you can ignore the lessons they teach entirely and push into a totally irrelevant field and make the most boring games imaginable that with enough marketing can still hit several millions while expanding their budgets.
The funny thing is, a competently put together, but very shallow combat system that follows the basic rules of game design in a game like demons souls and dark souls can still find massive success and people will still find themselves enjoying it even if it's barely more complex than something like assassins creed. Oh, and instead of trying to make everything look and feel cool, just a few attacks do, and people think all the more of a parry/riposte and the special attacks from some weapons despite how infrequent they are. Nobody dislikes the satisfactory drum, plunge and subsequent blood spray followed by flinging your opponent in those attacks, and they're just a little less shallow than what Ubisoft does.