People have a habit of becoming very attached to games they enjoy. Nowhere is this more evident than on sites like Destructoid or IGN where games are the main subject. This attachment, however, can turn out to be a bit counter productive if taken too far. Everyone is guilty of, or at least knows someone who is guilty of, having a game that they really enjoy and therefore think that it is beyond criticism. People can have the silliest excuses for this as well. Tell someone the story in a game isn't very good and you may get the reply “No one plays these games for the story.” Mention that a game's graphics are under par and you'll hear “Graphics don't matter, gameplay does.”
This sort of behavior is especially prominent in the comments of reviews as people tend to put far too much stock in the number score at the end of said review and how it compares to what they consider “fair.” The first thing that many people fail to understand is that a game should be critiqued on all of its merits, not just the ones it considered a priority. Just because Monster Hunter focuses on you hunting monsters and making armor and weapons from those monsters doesn't mean that you just ignore that the story is mediocre at best.
Video games have basic pillars that hold them up. Gameplay, visuals, story, controls; these are things that should always be taken into account. The ideal video game, I'm sure most would agree, would have a good combination of these things. That's not to say that a game lacking in one of those departments is suddenly a bad game though, there are plenty of fantastic games whose story isn't that great or whose visuals aren't up to snuff. But just because a game is good doesn't mean that the parts of that game that could use improvement should go unmentioned.
Here's another example: when Resident Evil: Revelations began making the rounds on 3DS and then consoles and PC, there was a lot of talk of how it was the Resident Evil game that people had been waiting for. After playing it for myself I mentioned in the comments of an article about the game that I personally wasn't a big fan of it. It was a solid enough RE experience, but I had a few problems with it, namely the writing and the fact that the second half of the game became 'back track a lot and shoot all of the things.' Someone replied to my comment (one of the writers from the website actually) saying “I must have missed the Resident Evil game that had good writing.” Then surely now would be a great time to start working on that.
If you've made a series that includes over 10 titles and not a single one is memorable for its story or writing then maybe you should consider working on your writing. This comes back to the argument “people don't play these games for the story.” Of course they don't, they don't have a choice in the matter because there isn't one with a good story. A good game with a good story is automatically better than a good game with a mediocre story.
This is where this story wraps around to become directed at you, the reader. Yes, you specifically. If you enjoy a game, even if you think it's the best game you've ever played, it never hurts to offer constructive criticism. The Souls series is one of my favorite game series ever but I'm not going to deny that some of the bosses in DaS2 proved to be way too easy, or that the second half of DaS1 was much weaker than the first half.
Giving feedback helps show that, while you enjoy a game that has been created, you still want the developer to keep trying to get better. That's the mark of someone dedicated to what they do, they constantly try to improve on themselves. You as the consumer should want games to improve, because you're the one spending money on the hope that you'll get your $60 worth. No one worth your money is going to create a piece of art, sell it to you, and then tell you they don't care what you think about it. Help them help you. Go forth and critique!