Because the current gameplay is so good and unique? Being a bad god of war clone would be a tremendous improvement for that IP.
Why does gameplay always have to be "unique"? Plenty of games are great with gameplay thats similar to others. Not that i've played many games that are like Ryse specifically, I enjoy the gameplay a lot in the single player and co-op for what its worth, put more time in to Ryse than any other game on my Xbox One. I think its a great game. Some people disagree, thats up to them, I can only offer my own opinion.
Another opinion I have is that I don't personally particularly enjoy God of War games - I can see why people like them, but I also don't enjoy DMC, Ninja Gaiden or anything others of that type of game. Theres very little of God of War about Ryse from what I can see (finished GOW 3 and Chains of Olympus for what its worth) and based on what i've said I don't see whats wrong with not wanting it to be like that.
I obviously hurt your feelings though, so for that I will apologise.