Part of this is because a lot of popular non-fiction (i.e. non-academic) comes from long form journalism. Personally, I like that style but understand that some people don't. The focus on that style is not pure information --- the authors aren't writing a textbook or a self-help book --- the authors are telling a story. I could read the wiki page on the Wright Bros, but I read David McCullough's "The Wright Brothers" because the writing is graceful and elegant and the storytelling is vivid and captivating.
The worst offenders, in my opinion, are the self-help/business books that aspire to long form journalism but are probably better off left as a bullet list on a blogpost. These ones are also infected by the idea that everyone of their bullet points needs a vague connection to some elaborate neuroscientific explanation and a "case study" that is usually some oversimplification. Cal Newport is painfully guilty of this, for an example; but it's everywhere in the self-help genre and especially in "airport" books. (I actually think Newport is a better blogger and occasional NewYorker writer than a book writer. His "insights" aren't that grand.)
Fiction, well, I think a long work of fiction is fine as long as the story can handle it. My tastes tend toward florid, "purple", and quite dense prose and descriptions. I like when an author "paints a scene". On the other hand, I find the recent trend of extremely "to the point", stripped down "minimalist" writing that is very common in a lot of contemporary literature (Rooney, for example) and fantasy writing (Sanderson, for example) to be downright boring and comes off as half-baked. There are probably too many 500+pg books because of publishers though. Fantasy has its own obsession with "epics". 200-250pgs is actually a great goldilocks zone that doesn't get published so often nowadays, but should make a comeback. The big publishers hate them though.
The worst offenders, in my opinion, are the self-help/business books that aspire to long form journalism but are probably better off left as a bullet list on a blogpost. These ones are also infected by the idea that everyone of their bullet points needs a vague connection to some elaborate neuroscientific explanation and a "case study" that is usually some oversimplification. Cal Newport is painfully guilty of this, for an example; but it's everywhere in the self-help genre and especially in "airport" books. (I actually think Newport is a better blogger and occasional NewYorker writer than a book writer. His "insights" aren't that grand.)
Fiction, well, I think a long work of fiction is fine as long as the story can handle it. My tastes tend toward florid, "purple", and quite dense prose and descriptions. I like when an author "paints a scene". On the other hand, I find the recent trend of extremely "to the point", stripped down "minimalist" writing that is very common in a lot of contemporary literature (Rooney, for example) and fantasy writing (Sanderson, for example) to be downright boring and comes off as half-baked. There are probably too many 500+pg books because of publishers though. Fantasy has its own obsession with "epics". 200-250pgs is actually a great goldilocks zone that doesn't get published so often nowadays, but should make a comeback. The big publishers hate them though.