Academics often complain about "sell outs," by which they typically mean fellow academics who have managed to sell books published by trade presses. (You know, the books you see in regular bookstores, rather than the ones that cost $485 each and are purchased only by university libraries.)
In my time in academia, people liked to point to Stephen Ambrose as a prime culprit. Indeed, as a young academic, I asked my then-colleague, Louis Pojman, for pointers about writing textbooks. At that time, Lou had dozens of them to his name, and earned a pretty nice income from them. His advice: focus on scholarly publishing, lest I get a reputation as "not a serious scholar." I could think about textbooks "when I got old and what my colleagues thought didn't matter anymore."
Though I didn't know these terms at the time, I think the "lean forward" and "lean back" distinction explains much of this tension. Scholarship is a lean-forward activity. But books published by trade press are more often lean-back experiences. Academics who find success in that area do so by crafting lean-back experiences in which the story propels the reader in a linear fashion. It's probably why history is the most common field for academics to find crossover success.
To be clear, I think there is value in both. Not everyone is or needs to be a scholar. Moreover, I'm fairly confident that a lot of the disdain for academics who write "popular" nonfiction stems from simple jealousy.
Most academics are terrible writers.
The result is a vicious cycle. Academics disdain popular writing because they are bad at it, and they continue to be bad at it because they disdain it.
Nonfiction is normally lean-forward reading. When the reader is in control, sequential ordering makes less sense. Lean-forward readers are drawing connections both within the text and between different texts.
An all-too-common view in the research and policy sector is that the IMRAD report (usually in PDF) Just Is the way that such materials are presented — that the writing of such things is timeless, independent of technology. Any attempt to change the report is met with accusations of "dumbing things down." The job of designers and technologists is simply to transfer the thing into the appropriate distribution channels.