As other commenters have noted, plain english is imprecise. When communicating with other scientists in the field it is often necessary to use language that conveys an exact meaning within their pre-existing body of knowledge.
If the audience is people without this knowledge, the precise meanings are useless and can be ignored and rigorous quantifcations are often unimportant. However, this is frustrating to scientists who are then left wondering which of n different definitions of some property/parameter you are using and how this influences results. This is critical knowledge when internalizing and applying new information.
I am also adding in many "over-elaborations" because the reviewer had questions that a simple adjective or two would have answered. A paper absolutely ~is~ a dialog with potential questions, and nothing illustrates this more than peer review.
The two audiences require different papers, and peer reviewers tend to fall only into one of them.