Non-RE/non-Horror fans & casual gamers enjoy it far more (many consider it the best in the series)

Makes sense to me, they are the target audience after all, the market for run-of-the-mill shooters is far bigger than for the pure survival horror genre.

I'm currently going through RE6 with a friend, and we haven't finished it yet. My opinion might change as we go on further through the game.
But for what I have seen, I'd say I'm enjoying it way more than RE4 or 5.

I'm a big fan of the classical survival horror RE games and was disappointed when I played 4 and saw that they changed the gameplay.
They did change the games to be action oriented, but they tried to compromise the gameplay with certain aspects of the older games that do not mesh well with the new style.

What that means is that they have you fight in an arena with lots of bad guys using a control scheme that was meant for slower more tactical combat. And the player ends up akwardly moving around the place and slowing combat too much.
Plus the hidden dificulty "director" that punishes the player for doing fine and rewards dying a couple times in a row.

RE 6 lets the player evade attacks by jumping and rolling like a maniac, moving around way more fluidly and generally making the controls way more dinamic and suited for an action game.
The story is also batshit crazy, which fits the new direction of the series nicely. But I'm not complaining too much about that in 4 and 5. I do believe they do that quite competently.

When changing the directon of a game series they might as well go full on with it and not have a middle of the road half and half conpromise that inherits the issues of both sides.

I don't think RE 6 is remotely as good as the first 3, but it is as far as I played the best in the second RE trilogy.