I generally agree but there is a counterpoint that could be regarded, too: younger generations have different consumption habits than their predecessors and an effort to make art accessible to a new audience is IMHO a commendable effort.
Now, that is not an argument for the new HP show (I'd love to see that franchise go to ruins and the abyss of irrelevance together with its awful creator), just a general thought I have when talking about remakes, continuation, new adaptation etc.

Progressing technology and changing habits impact different media differently, and there is a general spectrum from books (or written storytelling, generally least affected) to video games (generally most affected). Especially the latter has gone through enormous changes over the last three decades alone and I often wish there were more actual remakes of older games I never got to play but really don't feel like playing now because really outdated graphics and awkward controls are somewhat repelling.
And for movies and TV you can see a shift, too. I don't think The Lord of the Rings would have been made today like it was in the early 2000s and some movies (often adapting other media, but that's a different discussion) are already readapted into a more serialised storytelling for streaming instead of cinematic movies (e.g. Snowpiercer or Percy Jackson) while Disney is producing life action remakes of their animated catalogue.

That does not mean there is anything wrong with the source material, it just means a story is made accessible for a wider audience. Is the motivation for that a capitalism driven greed for money? Yes it is. Would these adaptations still happen in a world where artists would not be objected to monetary pressure? I do think so. Maybe not to the extend we see in our world, but maybe just with a different focus.

I generally agree with you, with one caveat. When a visual version of a book does not treat its source material with respect, and it’s a source material I love, then I’m okay with trying again. Some could make the case for HP falling into this category, I guess. But I’m thinking more along the lines of Disney’s Black Cauldron, an unholy mashup of the first two books of a series I adore, that not only disrespected its source material but straight up changed basically all of it. I would love to see a faithful adaptation some day but I suspect I never will, so I’ll keep rereading it every ten years or so instead.

Remaking things that were originally visual media, though? Or remaking anything in the same format it appeared in originally? I tend to agree with you. Extend the story instead if you must; skip the rehash. And we’ve seen the trap that these mega-franchises get into when they can’t escape what they see as the gravitational pull of the original.