Its for these reasons where I don't have a preference between either game.
It seems this change was to make the sequel more inline with the comic books, rather than following the 'spinoff' story that the first game started, especially since the second game also went for a comic book artstyle that completely ditched the "gray & brown" of the first game. Having Jackie be way more talkative with a new voice actor really soured that image we had of him from the first game, that introverted, quite man. However, the story wasn't as strong in the second game. You have way more abilities, and ways to use The Darkness, gun play is much faster with now aim down sights, and being the game is on PC, you don't have to deal with sluggish analog controls, which was a big problem in the first game since it only released on consoles. Yet, in the second game, gameplay is so much better. It was basic 1st person shooters with some abilities with The Darkness. What do I mean by this? Well, the first game had decent gameplay, but it wasn't completely revolutionary or special.
Sure, both games are a linear 1st person shooter about Jackie, and his adventures with The Darkness, but one is more like a movie based experience, and the other feels more like a game. I think the biggest thing for people is that both games are a different experience. These videos were essentially saying why the first game was better, and many seemed to agree on it. Around 6 months ago, I was recommend two videos about The Darkness vs The Darkness II.