Yeah, there is some self promotion in MGC. Isn't self-promotion every writer's responsibility?
Charles, Freer also notes that L'Amour maintained a single PoV, rigourously. This argues against lack of craftsmanship, and for the idea that L'Amour had a different sense of what is done well and what is done ill.
I can enjoy Beethoven's Grosse Fuge, and have enjoyed it immensely. I also enjoy the music from Les Miserable. It's not the same craftsmanship and art as Beethoven, and the composer made a big change of technique, building the whole work around the interval of the fourth instead of the fifth. The musical fate of that interval tracks the fate of the protagonist.
That more people rather than fewer can enjoy a thing, and will pay for it (giving up the fruits of their labor in trade for it) should not be taken to mean that the thing is a poorer piece of work. The Grosse Fuge is a greater work than the score for Les Mis, but this is in spite of its difficulty, not because of it.