Old writing is used as a source because there's nothing new under the sun plotwise. Just as easy to say that its not derivative so much as it rose organically.
You are sort of all over the place on your points. Several of your authors were popular writers at the time. So to dismiss popularity as equivalent as not significant is a stretch.
I would disagree you need to read Homer to appreciate modern authors. I think a lot of dismissing modern authors is done with the same sort of mindset as dismissing modern pop music is done its sort of an argument by appealing to tradition instead of judging something on its own merit.
Take someone like prime Ellison. He would stack up comparably if not favorably with any author you mentioned.
I have read most of the works of every author you listed. Reading is perhaps my favorite method of time passing...if not wasting and I still can enjoy King work's as much or sometimes more than Twain who I like or certainly than Melville.....Homer or Joyce....meh I would prefer not to.
Dismissing works as too simple or derivative is I think shortsighted. Time passes tastes change the artist as a young man isn't the same as he is when he gets older nor is the person.
Genre fiction is also strange to rate quality wise. Take something that was early like Tolkien which was early and significant...but frankly written poorly. Someone like Rothfuss or Martin is a better slicker writer and in my opinion a better read. It doesn't mean Tolkien isn't worth reading but if given the choice why not read the more polished writer?
How often do most of you that are claiming significant value in reading in the canon do it I wonder? Is it worth reading Bartleby only one time? Is it too much to reread The Great Gatsby...I'd argue it a waste of time to read once but that to each their own.
What particular value other than historical do you see in Huck Finn versus The Hunger Games? With no appeal to tradition or the canon why is the historical journey of a boys coming of age superior to a perhaps predictive dystopian coming of age story of a young girl. I mean if I were a young girl a female protagonist could very well appeal to me more.
The one point I align with you on is that paranormal romance is a terrible genre and I can't believe anyone likes it, but then again I like bad kung fu movies so who am I to judge Twilight.