Overall pretty valid criticisms, I am able to enjoy the game pretty well because my expectations were very tempered, and I still find it to be enjoyable in most of the Bethesda ways I've come to expect, which is really a culmination of too many small touches for me to exert the effort of writing down and cataloging.
The only thing I'll say to all of that is that when you said that the writing quality wasn't what we expect of Bethesda or a mature game, that's a bit silly. I'm a Bethesda fanboy, basically, and even so I've only ever expected serviceable to middlingly poor writing out of any of their games, and that's about what I feel the internet expects as well, not that that makes the criticism invalid, the writing is... well, serviceable at best or middlingly poor at worst, and I don't really come in with any expectations for good writing out of a game rated mature, either.
All a mature rating means is whatever specific traits are listed on the rating, leisure suit Larry box office bust is rated mature, and that game's writing is not emotionally mature by any means.
You are correct about most of these issues, though. Somehow, by sheer amount of story content and stuff to acquire and build, I'll probably still spend about a hundred hours in it before modding, and modding will probably take it to unknown lengths. I do believe when Todd Howard says the game was made to be played for a long time that he's indirectly talking about the mod support and the game's premise and interplanetary setup being the most ripe for user generated content, and I believe that that'll add much beyond the game's natural life, in an even larger ratio than older Bethesda games, which is its own possible criticism.
Even still, I'd have to say that the game lets down on enough critical fronts that it'll be my least favorite Bethesda game, with the top two spots going to Oblivion and Fallout 4, for me, personally. I do also have to admit, when I look at the big picture, getting more than a hundred hours of enjoyment out of a game, even for the full $70, is good value for time spent, to me, and I do enjoy the game. I don't enjoy it massively, but I can spend time in the world and accomplish tasks and feel satisfied, or enjoy the gunplay or conversations enough that I can't complain.
I've bought other games of higher critical opinion that I spent far, far less time in, and didn't get the same amount of cumulative enjoyment out of, because they just don't tap into my brain in whatever primal way that Bethesda games fit in, even Starfield, puzzlingly enough.