While there is some truth to that, too often to me the modern readers assertion that what they glean from a text is what matters and not what the author intended to say strikes me as a combination of laziness and narcissism. I very much feel that the "death of the author" is just an excuse for no longer approaching a text ready to do the work and rigor of figuring out what it says. If you claim that the author's intent doesn't matter and that the meaning of the text is what you absorb, then you are excusing yourself of a lack of all reading comprehension.
I do appreciate that you seem to admit that a good author conveys their meaning clearly as that is a more nuanced take than I tend to encounter, but I suspect that poor readers will tend to claim all authors are poor ones.
Nice to see I succeeded in conveying my disagreement with my peers without actually stating it...
Seriously, I will note that the value of Tolkien isn't what he intended (even as he's succeeded at his once stated intent - a new English mythology) but how the ongoing fanbase accepts and interprets it. Especially his biggest fan-fiction author, Christopher Tolkien...
L5R was intended for players to go full-weaboo and as much Pre-Shogunate Imperial Japan as they can do, while setting it in a fantasy land so that it's not using the classic names, and encourages full on cultural appropriation while excusing error via "Rokugan is Not Japan." (Capitalization important.) (Rokugan can be translated, depending upon kanji, 6 eyes, 6 rot, 6 cancer... 6 rocks (tho that mixes reading types - kunyomi vs onyomi- tho' I've seen evidence that John has used mixed readings in charcter names.) John's intent was mixed parties across the clans, either on the wall or in the winter courts, at each other. He succeeds at conveying this "intraparty strife" to only a few... but the rest is well conveyed. Did he fail?
NO! He didn't fail. He wrote something that (A) fed him and his spouse for a while, and (B) is still generating more fans. And fiction.
On a commercial scale, John's intent was meaningless. The company's intent was: to sell books about making cool samurai and having them have adventures putting duty, glory, and honor at odds with each other as calls for character actions... many glorious acts fail at Duty or Honor; Many honorable acts fail duty or are inglorious; many dutiful acts are dishonorable or inglorious.
As a recovering English literature graduate student, I could not possibly be more thrilled to see this discussion here.

. But at the end of the day, aren't RPG manuals instruction manuals? If the authors fail to convey their meaning, then that is a failure on their part.
Only if it fails to generate meaning for the reader. After all, billions of people derive meaning quite divorced from the probable intent of the authors of various "rules for living." With the exception of Abū al-Qāsim Muḥammad ibn ʿAbd Allāh ibn ʿAbd al-Muṭṭalib ibn Hāshim, and of Moses ben Amran, most of those using the rules enshrined in writing do not even read them in the original languages.
As a GM, I really don't care what the author's intent was - I care how the rules impact my play, and if they're playable in my playstyle range and tolerable to my players. (Who won't hesitate to tell me when they dislike the game.)