the exact reasons and complaints that i had about the game, it gets to repetitive after a while (even if you can tackle a mission in a million different ways if you keep doing the same missions over and over for dozens of hours it will still end up feeling repetitive), and completely agree on the pacing problems that the game has, (that was my original complaint), i sometimes played for 5 hours doing missions and i got not a single important cutscene that would actually move the story forward, only more missions that would (In Kaz words) "get us closer to cipher or skull face", and then when i was tired and about to turn the console off a cutscene would trigger and the game would move its plot forward and throw an important mission on my face, and i would be to tired to go on since i would have been playing for hours and was just about to quit the game for the day.
And i do agree that the story was always the biggest reason that kept me invested in the game, however i always liked the gameplay in MGS and i always had a BLAST playing all the games from a gameplay perspective, and MGSV gameplay is surely the best one so far and by far (therefore i do disagree with your last statement), the gameplay was great and it keept me enterteined for over 90+ hours until i started feeling how repetitive and bad paced the game was.
That's why I fell in love with MGS3, despite its flaws. It absolutely upended the "too many cutscenes" stigma Kojima has attached to his name. The gameplay wasn't mearly good, it's one of the best action games, from a gameplay perspective, I've ever played. That is not a compliment I dole out often, as many here are aware. I am very critical of everything, and even I couldn't help gush over that game. There were definitely a lot of cutscenes, but it was, for the most part, expertly paced. There were only two occasions where I felt that they were in the way. Outside of that, they always came right when I wanted a break from the gameplay. Every. Single. Time. And never, on those occasions, did they overstay their welcome.
I think that, mechanic wise, it's the best. (Well, better than SE) Snake controls better here. 1) But I will debate tooth and nail the sentiment that the open world absolutely ruins MGS's brand of arcade stealth. Maybe this is blasphemous to say, but playing a mission in MGS3 felt exactly like playing a level in SMB to me. It was relatively linear, and a very choreagraphed experience. That made it great. MGSV trades that tight choreography for player agency, and I don't think the game benefits enough from it to warrent the change. 2) I think regenerating health was a terrible compromise that completely shadders the tension found in earlier games and promotes hit and run tactics. I think that supply drops absolutely destroys any incentive to naturally explore the areas you're infiltrating for more than just the specific targets you're looking for. I played for maybe 20 hours and there were absolutely no interior buildings to infiltrate, meaning I literally only had two settings in that playtime: Desert and Safari. Because the levels in Snake Eater were so linear and choreographed, every single mission felt vastly different from the last with their own gimmicks to factor in, the same way every level feels different with their own gimmicks in SM3DW. The idea of that is laughable to the point of ludacrisy in MGSV because they're so focused on so-called "emergent gameplay," which already existed fine in MGS3. Really, I want to think the open world ruined so much of this game, but I genuinely think we could have gotten the best of both worlds somehow. 3) Maybe a smaller, denser, Dark Souls/Bloodborne approach to level design where the areas and routes are, by definition, linear, but all interconnected. I don't know, but what they did here ruined much of what I liked about Snake Eater and I imagine much of what I'll like in the other MGS games.
Also, the bosses suck.
Like I said, I'm glad you enjoyed it. The fact that I lasted 20 hours shows how much I enjoyed MGS3, because if I hadn't, i would have stopped after 6. That's how hard I was hoping it would get better.