They don't even really give you much of any concrete guidance on how you might change a design to make it more fun if it isn't currently. The best attempts at this tend to be along the lines of looking at certain player profiles and trying to imagine what about your design appeals to those who enjoy that profile.
It's possible that this isn't something we can easily quantify.
If I asked you to write a book about what makes music good, would you be able to do that?
Nobody ever got told they were an amazing composer because they followed all the rules. You can be good, but the greats all redefined something about the common practice of their time. However, if you stray too far away, people find your music too alien and tend not to like it at first. History is littered with references to new music from composers we now consider to be truly magnificent, who were at the time considered to be merely mediocre, or whose innovations were not welcomed with open arms.
And of course, computers are still terrible at writing lyrics. That's an entirely different game.
Maybe one day there'll be enough video games and literature that we can formulate a video game theory which is as extensive as our modern understanding of music theory. The thing with music of course is that we've been doing music for a lot longer.
My main takeaway from it, if I had to boil it down to one point, is your brain finds fun in mastering something (beating a challenge), but not so much afterwards (boring/repetitive) or if it's too difficult (frustrating). The problem is, where that line is for any given challenge can be different for everyone. You can also get more mileage out of something if an aspect of the challenge changes (people will play chess longer than tic tac toe for example, even though the game space is the same each time).
At Ghost we often find ourselves looking at a proposed or newly implemented feature and asking out loud "but, is it fun?". The answer can be very difficult to find, especially since many great features aren't fun until they've received that final layer of polish.
And here's part of what Zelda does so well. You can see how a lot of the great things in Breath of the Wild would be great fun even in a simple prototype. On the flip side, this kind of exhilarating feeling of being able to do so many cool things only works because every single piece of the game is designed with this in mind and all the crazy interactions people come up with are actually supported.
It only works so well because people aren't getting that familiar feeling of "oh. That didn't work." This must have been a massive task and I'm amazed they pulled it off!
[1] http://www.polygon.com/2017/3/1/14780954/the-legend-of-zelda...
I can't begin to tell you how many times I come up with this clever idea, mock up a bunch of components or start coding a prototype, and go... "oh, damn, this isn't much fun." I've been able to whip a lot of those failed ideas into something fun, but it often takes a lot of experiments with different ideas or borrowing pieces of designs from other games that have worked, a lot of time and rumination on the design (I get a lot of my ideas for new things to try while walking my puppy, commuting in a quiet car, or in the shower), and putting it aside to work on something else and letting my subconscious or things I encounter in life to inspire potential solutions to the problem (and often it'll still take multiple attempts to fix things).
The ones that drive me the most crazy are the ones where you try it for the first time and go 'This isn't that fun with this set of rules, but it's close to fun. If I can just find the right tweak, this can be great.' It can sometimes seem like it takes forever to find that right tweak. I've got some prototypes that I think are almost there, but I've had to put aside because I spent so much time on it and still couldn't figure out the right tweak for them.
There have been attempts to nail down Game Design principles. There are quite a few books you can get on Amazon that have some good insights in them, GDC lectures, Gamasutra articles, academic journals, etc. There's nothing that's totally universal, but the more you learn, the larger your design palette to draw from.