It's the important part, it's not the difficult part.
Like "I want a square, four tier cake with baby-blue royal icing, using a light fruit cake". That's super easy to say, hard to achieve. But the vital bit is contained in the simple definition.
The only other thing to say at this juncture is that in general there are two experts, domain-expert and programmer.
>I just need to grunt some sounds to express what I want and a writer can tidy up the details //
Well yes, we already have algorithmic story generation (eg ScienceDirect webpages), you "grunt" the topic and the program fills in the details.
I want a thing which will be a centre of attention at an appropriate moment of their existence which their senses will experience .. an appropriate sensation to convey .. to achieve the appropriate goal of goodwill, at an appropriate amount of resource expenditure?
Does that still cover the important bit? If I say I want peace among nations, have I just done the important bit of international diplomacy, and it just needs some experts to tidy up the details?
The whole reason for the existence of iterative processes like Scrum and friends is that your premise doesn't hold in the world of software, because then we could just use a waterfall process and be on time and budget every time.
Poser is one possible “3D human in a pose” software since 1995, like python and Delphi and Visual Basic are your rapid application development (RAD) tools that have been trying to do “programming as doodles” for years.
By the point you say “lex-parse process” you’ve already narrowed the scope from all possible software to a tiny area and used a lot of expertise to know that’s even a thing.
Choosing arrangement of 7 English letters has 8 billion or so possibles, “real words which people probably know” is four or five orders of magnitude smaller space of choices; maybe I just need to grunt some sounds to express what I want and a writer can tidy up the details of my comment later. But the choice of words is dozens of small choices which are inseparable from expressing myself. A writer, a consultant, doesn’t make your idea, they make their idea of your idea.
An artist could surely tell you why the choice of clothing doesn’t work, but the time you’ve got your artwork expressing what you want to the level where the choice of clothing fabric is the only thing left to tidy up, you are an artist already and have saved none of the important effort. You’re hiring Mozart to tell you why b-flat sounds off some fourteen minutes into your symphony.
It’s like gaining expertise is narrowing a space of options by orders of magnitude until we can jump close to a solution quickly. Being a non-expert is like assuming there is only a small space of possibilities that everts deal with and if we try to solve the problem we must end up in that space too and then all we need is an expert to nudge us to a settled location nearby. But instead we don’t see how big the space of billions of possibilities is and we go very far away, and an expert can only do the hard work of moving our solution to the space of possible answers - which is basically all the work and almost no better than starting from scratch.
It’s almost like we need the expert to jump near the solution space and then the non expert to nudge the details towards what they’d prefer. The program draws for you and you chose the clothing fabric and lighting. Like a computer game avatar generator where you just choose the hair colour and T-shirt colour - and equally unsatisfying because it’s not at all like you imagine you could express if only you knew what the expert knew.