Rather than being fleshed out, I think it was the pacing and the progress of the story. For starters, I assumed the story wasn't meant to be a "heavyweight" thus, the author wasn't being particular about being in depth about the supposed to be issue. And I believe the author's note was talking about his adventure on how he went from writing a good plot based story to how it ended up like this since this was an r-18+ entry submission. Plot wise, I do suppose it was intended to be quite "fleshed out" since Lezhin does keep a reader control on its stories, or so I've heard. Otherwise, this story would've become.much more emotional and quite angsty but with a happy ending. Tbh, I'm quite contended with the ending since I guess this is the author's first serialization, so there's much improvement necessary.
Thanks for the external context. It does affect the way I'd see the story now a little. I also understand that it isn't meant to be heavyweight, it's the explosive drama that made it too complicated and i think the author tried to patch it up. It just didn't work for me. Their next work looks promising tho :)
And it's my lack of interest for how the story went. It began really well but when the smut and the complications were being "fleshed out", it felt half baked, like a plot for some porn where it doesnt even have to make sense. the uncle-nephew is being thrown out the window then conveniently used to add some drama. Like the uncle is so annoyingly imposing his whims, insensitive to the matter at hand while he loses his sanity in sex. Then the rape occured but make it dubcon cause the uncle wanted it (way to make a rapist out of your nephew and it's just so pitiful to watch the nephew internally hate it but encouraged to continue anyways) And then conveniently time skips to just a month coz all is well but never really addresses the "we're unCLe and nEPheW" until the very last side chapter (which is also a convenient time skip