I'm usually kind of all over the place with my points. I'd be surprised if there isn't a third or fourth separate issue in there somewhere.
I'm just glad I've had three responses so far that have been pleasant ones
I don't think Lewis, or any reasonable person, would have a problem with adults enjoying kid-oriented fiction, YA, whatever. I do think he'd have a problem with adults liking it because they're supposed to like it, because it's the "thing to do", because they'll fit in more with the youth crowd, because it makes them feel or seem younger/cooler, etc. YA fiction is a demographic now much more than it used to be. With the movie tie-ins, the mass cultural acceptance of grown ups acting like kids, it's understandable that there's some pushback from people like Ruth Graham, questioning why YA is mainstreaming with adults. I tend to try to see the big picture, connect dots where there sometimes (?) might not be connections but sometimes I get lucky. Generational (and gender) lines of interest are so blurred now that it's hard to keep track. Bronies are a thing, fer Ghod's sake. It all just kinda makes me feel like I'm gonna hurl, ha ha. (irony)
A character in Gorgias (not one of the "good"ones) is talking to Socrates about adults acting like children, and he says such people deserve a whipping, ha ha. He also said that hearing a child speak as an adult makes him uncomfortable, because it's unnatural. While I don't absolutely agree with him, I do see his point. Seeing 50+ year old skateboarders, men in shorts with their baseball caps on backwards, it's just goofy. But whatever.
Someone brought up The Westing Game. I only just read it for the first time probably 5 years ago. And I'm 48. I enjoyed the heck out of it. Some YA stuff holds up when one reaches maturity, some doesn't, of course. Artificial/inorganic/cloying vs. The Real. It's a constant battle.