Meh, there's a real magic to watching actors age in "real," in-universe time that animation just can't match.
In your opinion as a viewer. If you were a TV producer who had to mount a multi-year series centering on child actors, you might be concerned more with pragmatic issues than such subjective ones.
The mainstream American public, which would have to be a key market for a show with this much theoretical mass appeal, has not shown itself to be interested in animation for long-form or dramatic storytelling.
Umm, Harry Potter is a children's series. There have been a lot of successful long-form children's television series in animation.
Yeah, but the later books should have been a lot shorter.
That's not the subject, and it's a matter of opinion rather than fact, so I have no interest in debating it. I'm talking about the first two books and the objective
fact that they are extremely short and simple compared to the others. The concern is that devoting an entire season to each book might require padding the first two out considerably, and that could make for a weak, meandering beginning to the series. Imagine if the first Tolkien films to be released had been the
Hobbit trilogy.
Fun fact: the general public is just a wee bit more familiar with the Harry Potter books than they are with the Expanse books.
The audience's prior familiarity should never matter. Every work of fiction should be made to work entirely as its own self-contained entity, accessible to newcomers without requiring prior familiarity with the work being adapted. That's the whole reason most adaptations change things from the original -- because the priority is what the
current story needs to work as well as it can, regardless of how the source material handled it. The
Harry Potter movies were the exception in being as faithful to the books as they were, and even they made major changes in the later films. The series will be its own entity -- it won't be the books or the movies, but will be a new work
based on the books. So its priority should be to structure the story in the way that works best for
itself, rather than merely copying something that's already been done. Why even bother doing a new version if it's not going to tell the story in a new way? (See
Game of Thrones, for instance. The first few seasons were close to the books, but as it went on, it diverged more and more and eventually became its own distinct thing.)
And, since each book covers one year, it would be ridiculous not to group each set of episodes by season/year, no matter the release schedule.
"Ridiculous?" There have been plenty of TV series that don't progress in real time.
LOST's first four seasons covered only 100 days of story time, flashbacks aside.
Young Justice's second season was set five years after the first.
And there's no reason a single broadcast season can't be subdivided into distinct story arcs, like
The Flash's use of "graphic novel" sub-arcs in its recent seasons. A lot of recent network shows with long midseason breaks have tended to divide their story arcs into two half-seasons, so that a single broadcast year contains two complete, successive story arcs. It's actually quite common these days, so it's bizarre that you think it's impossible.