To be fair to Jobs, it can be profoundly difficult to communicate visual design principles. At least when given the opportunity, Jobs sat down and actually put his hand to the design work. It's debatable whether Espinosa spending his time building a parameterized-calculator-constructor was worth the opportunity cost, but at least Jobs made use of it, which is more than you can say for a lot of executives.
On the other hand, this seems like something that could've been hashed out on a whiteboard or napkin...
Anyway, I think the real hero here is Espinosa, a programmer who took charge of documentation and the user manual, and went about his work by dogfooding his product (Quickdraw in this case).
How so? Pencil and paper were readily available in '82, what else would you need?
Who knows--The original calculator could have looked like the one in Windows.
(And why can't it be both relentless devotion to perfection and anal retention? Some people just happen to have refined tastes and the power and intelligence to wield it.)
(Then there is also the question of form vs function, about which I'm getting a hint of you being more on the function end of things. All these questions of "better" and "worth it" can only be answered within some value framework.)
Furthermore, if he wanted to communicate how the calculator should have looked, he could have DRAWN it.
The developer made a tool which let Jobs rapidly iterate through a number of ideas until he saw what he liked. There's no reason to believe he knew what he wanted until he could experiment in a low-friction manner for himself. That's what the dev gave him.
You can't iterate through something without parameters and do the same. Look what happened to me: http://i.imgur.com/rCHiZyR.jpg
No one is going to argue he wasn't a rampaging narcissistic asshole. Even so - it makes no sense at all to ignore how much he steered the look and feel of Apple products, and of late 20th/early 21st century design in general.
He was the only person working in computing with a consistent interest in design. Microsoft and IBM had zero interest, DEC had a minor interest in making nice-looking minis and mainframes, and the 8/16 bit micros often had some product design applied to the casing.
No one else was thinking about software and GUI aesthetics at all.
The problem here comes in the nitty gritty details. Short of a pixel perfect drawing, there's no easy way to convey what you want in specifics. And then there's the difference between the mind's eye, paper and screen. What looks good for the first two might not work on the third. Getting a parameterized version to modify allowed him to drop the paper/speech part and go straight from mind's eye to screen.
Are you aware that the stories on folklore.org are written members of the "original mac team"? In linked story -- by none other than Andy Hertzfeld -- describes Jobs as acting "in his role as our esthetic compass".
The keyboard and (optional) numeric keypad worked, too. That gave you a calculator that had a better keyboard than that $5 one (did that exist at that price point in 1984?) and, admittedly, less functionality and lower speed (but you could copy-paste results into the scrapbook within a minute or so, often even without switching floppy's)
Also, this, the puzzle and the control panel (setting the desktop pattern!) were so cute that they ate time like flappy bird or angry birds in their heyday.
But most importantly, the thing had to look that way to make ordinary people the step towards a GUI.