Because the point of the chapters in a book is that its a series of events and progress. From a purely artistic and creative medium, slow chapters have to exist with high action ones to create a rhythm and flow which ultimately makes the overall quality better. If you're only getting high action all the time, it'll wear down on you. This is basic creativity 101. You find this philosophy in virtually all mediums - food, books, movies, music, cartoons, comics, and yes games. So some chapters are gonna be slower, and yes there is a little filler at times (which can probably be axed). But just skipping ahead in cause "oh this is boring" demonstrates that the consideration isn't the story, but rather just the punchline. Imagine reading Harry potter, but instead of reading the books, you read the first few pages of book 1, and the last few pages of book 7. You skipped everything in between cause 'oh it was boring'. At that point, why did you even read it. You weren't concerned with the journey the character makes, or the world that was crafted. It just gets summarized into a few pages.
Perhaps this is my own personal bugbear and bias, but from my observations, people who skip over all the content cause 'it's so boring' are the same people who weeks later complain about how come there's nothing to do. Game offers you a rich journey, and you pressed fast forward on it and are dissatisfied that there's nothing left.
You're viewing this in the wrong light on three parts:
1) From a purely business standpoint, its in SE's interest for you to play out the MSQ because it means longer sub times, either through time spent or sheer interest. So of course they're not going to just be like "Here, skip all this" without some level of compensation.
2) For game health, you want to discourage newer players from just skipping right to the end. Like it or not, the MSQ still forces players to learn certain aspects of the game. This cuts down more on getting people in higher level content that don't know how to play the game.
3) You literally paid for content and then are saying "I don't want it, allow me to skip it for free." That's not how the game was set up. Name me a single player game that says "If you don't like this, just skip it all together!" that hasn't been mocked for that kind of feature.
Theres a difference in QoLs. A QoL with streamlining some of the games mechanics is one thing. If you had to jump through 20 menus just to adjust the volume, that could use a QoL change. And not all 'QoL' changes are healthy for a game. Use wow for an example. When they implemented that you could queue for dungeons anywhere, it drastically hurt the world map. People just sat in town at that point waiting for queue times. It made things more convenient, yes, but hurt the game in other ways.
The nuance, I suppose, is maybe trim down some of the MSQ in ARR in 2.1-2.55. As I said, there is some filler, and some of that can be abbreviated a little. But I think just skipping the MSQ all together for free for new players ends up hurting the game by hurting retention. If you cant get people interested in FFXIV with ARR, then they're a lot less likely to stick around long term as is. The story becomes secondary to game play that already isn't really unique. And when you don't have to work for anything, don't have to invest, you don't care if you give it up.