The answer is that software development is complex, and I'm not just talking about the actual nitty gritty of design or implementation. Frontier are a business, and like it or not they have to prioritise where they put their resource. Said resource is finite, often specialised, and the business will be generating competing demands for it. Frontier have three ongoing franchises (Elite: Dangerous, Planet Coaster and an unnamed third "Hollywood film" game). Given Planet Coaster has released, it makes sense that much of that third franchise will be made up from resource that previously worked on PC.
We also have to consider that sales are important: they're what drive further investment. As sad as it is, Frontier already have your money and taking a step back and concentrating solely on QoL for existing players doesn't make a lot of financial sense. What *does* make sense is for them to continue to develop new features and pick off the QoL changes as they go. This generates new money, which feeds back into the game in the long-term. Of course there are risks inherent in a strategy like this: put off your loyal customer base too much and you'll damage your relationship when you want them to spend more money later.
What we're seeing in the PC update model is that these minor point releases contain some of the more vital fixes, with the occasional bone thrown here and there to keep things interesting (such as new flat rides or the terrain collision update). Adding new features to a maintenance branch is messy, which is why we'll see the majority of QoL fixes in the major point releases. The terrain thing probably turned out to be a fairly trivial merge from the trunk to the maintenance branch, so the engineers decided it was low-risk enough to include.
As to your comment / question about the code base becoming so complex. Yes: the code base will be complex, and necessarily so. But the whole project structure is complex. Any particular feature requires the input of teams from disciplines such as: UX, engine, game logic, art, animation, audio. If you want your catalogue to be recategorised or reordered, that probably needs the involvement of UX and game logic teams (and possibly engine). To make those changes you have to schedule time and dependencies of those teams, bearing in mind the overall business need for them. You also have to ensure that they're compatible with other changes that you plan to make, to ensure that you don't do the work twice.
The team won't be blind to the game's shortcomings. They won't be *happy* until it's as perfect as it can be. I've talked to Matt about the audio, and how wonderful I think it is; he points out the flaws that he still knows are there, because that's how it is with engineers. They have to live with the day-to-day reality that there'll be some things they never get around to doing, or that there'll be features that necessarily need to be prioritised over QoL fixes. They have to make those changes and QA them. They have to deal with the issues that look simple on the surface but that require complex or time-consuming refactoring. They have to try to figure out what's going to give the community the best overall improvements, while balancing the fact that everyone wants something different. They don't just say "bosh, done, job's a good 'un" and leave it there.
I'm certain that Frontier are aware of their shortcomings, and I'm certain that they wish they had more time or resource to invest into the game. But I think that it *does* show commitment from the business that we're getting these major feature releases. I think they *have* shown that they listen to what the community want. Most importantly, I think they've shown that threads on the forum that critique the game and suggest improvements *are* welcomed, and that they *do* want to improve things. It's important that both sides of the coin are represented, that there are threads showing gratitude and those being critical. Gratitude improves morale, and gives the team renewed vigour to continue. Criticism gives them focus and reduces complacency. It also makes for a healthy, balanced community.