In most instances, I assume the writer simply lost touch with the intended audience. That can happen fairly easily when someone is accustomed to juggling several different audiences with variations on the same themes. Although presented differently, the text should be geared toward the same level of expertise. Cut to the chase. Condense your text and avoid extraneous information.
Shorter messages are more likely to be read when they are opened.
Longer messages are frequently set aside to be read later. And sometimes later never comes. Focus on change. The channel partner needs to be able to get an immediate handle on how the product, service or program is going to be different. If that isn't abundantly clear, go back to the drawing board.