This topic refers more to game design, which I agree actually. The very beginning vision that is set out to make a game is the most important thing. More important than gameplay.

Let's take MGS3 vs. MGS4. Both games have great gameplay, but the controls in MGS4 are far smoother and precise than in MGS3. You even had access to more customization options in MGS4.

However, even putting aside story differences I felt the world and approach to MGS3 was just far more interesting and engaging.

I agree.

The experience is the most important thing. Showing me a good time, a game doesn't achieve that necessarily by it's gameplay. Journey barely has gameplay but it was my GOTY of 2012. Same with Walking Dead, Heavy Rain, To the Moon, an entire genre called visual novels, walking simulators etc lack gameplay yet are beloved games.

If you take away the graphics you're not left with a bad game, you're left with a blank screen :p That would somewhat defeat the point of a video game.

Gameplay is the most important thing because it is what define games. A game without gameplay is just an animated movie. An animated movie can still be a great and immersive experience but why should I spend 400€ for a console and 60€ for the game when I could just buy a 6€ movie ticket?

I agree. I remember when I first played a game by the name of Panzer Dragoon Saga. It came on four CD´s but was only about 15 hours long because of all the cinematics. If it hadn´t been for the utterly amazing gameplay, It would only have been a great story that you play through once. Thanks to the gameplay, it became an immersive experience that I went back to numerous times.

I think that interaction, whatever form it takes, and a failure state, implied or actual, is the most important element. If that's how you want to define "gameplay," than I must disagree, it is most important because it is the very definition of what a game is. To remove all underlying principles that define the bounds of a medium is to do the medium a disservice. Recognizing those bounds, those principles, is what allows the medium to advance and provide that unique gratification that only that medium can provide. TV, Movies, traditional Art, Theater, Music, all these art forms provide unique gratification that the others cannot through use of unique aspects the others lack. They have progressed by recognizing that. In games it is the same. You can't just focus on "the feeling," but rather the unique gratification and more importantly, it's source. And I believe that interaction that promotes player investment is that unique aspect. If you lack that, then you sacrifice the most important aspect of a game and it becomes a less powerful representation of the medium. And the more you use that unique aspect, the more potentially potent that gratification comes.

The story isn't part of the gameplay. The choices are. The story is the why. Rescuing Princess Peach is story not gameplay. 

I was going for the overly simple definition of gameplay there to make the point that most people who say it's the all important part often include much more than gameplay when they say gameplay.

I know what you're trying to say, but I'm going to be annoying and state that if those games lacked gameplay then they wouldn't be games in the first place.

I'm not trying to be pedantic, but I think that what made these games so good was that even though their limited gameplay mechanics, that gameplay still was the cog that moved the experience along and allowed you to be sucked into these experiences more than if you were just a onlooker and not a participant.

Like, for example, I'm playing the Phoenix Wright games right now (on Trials and Tribulations, and it's very good so far), and as a visual novel style game, it's main focus is on the stories (and the mysteries that must be solved) and the characters, as opposed to a Mario Bros. game, where player interaction and control is the main hook of those games. However, the Ace Attorney games (and all the games you mentioned) are still moved along by the player. It is you that turns the cogs of the game through your interaction (and so the gameplay is intertwined with the story and characters. And vice versa). So the player's participation is still an essential aspect to the quality of the game.

Games will less gameplay must still have gameplay that supports the other aspects that the game wants to put forward. If the interaction aspect doesn't support the rest of the game in a positive way, then the game will still fall apart, despite how flawless the other aspects are. As much as I am enjoying the Ace Attorney games, with their neat stories, mysteries, and characters, there are gameplay issues that are keeping me from enjoying it as much as I could.

Anyways, as others have said before, I now feel like I'm arguing something that the OP wasn't arguing.

I just wanted to put forth my own thoughts on why I feel that gameplay is an essential piece of the gaming experience, and that it's always an important aspect in how we judge all games.

No question - a good game is good because of many many reasons. But it is a game because of the gameplay. Good gameplay doesn't make a good game every time. But no gameplay means no game, and bad gameplay ruin games.

As I said, there are already games without graphics, that rely on hearing. That is used by blind people for instance. Also many would say, that a purely text-based game (Infocom) has no graphic.