In workshops, nobody argues against plain English, but it's a different matter when we look at examples from their own organisation. That's when the defences come out. They worry that writing in simple, everyday language will create the wrong impression.
The wrong impression? They usually mean creating the impression that they are not well educated or lack authority. If you are looking for respect, don't try lofty academic language or the stuffy language of bureaucracy - commercialese. The best plan is plain language, nothing fancy.
Make your language technically correct and, if your readers understand the jargon of your business, use it. But impress them with the clarity of your writing, not the words you know.
Here's a useful test of your writing
Would you use that language a conversation or presentation?
If your report is going to a formal board, council or executive team meeting, imagine you are presenting your ideas at that meeting. Your language will be slightly more formal, but not enough to seem like a lofty academic or a stuffy bureaucrat.
Does lofty or stuffy language really harm our reputation? Yes.
Here's objective evidence
Daniel Oppenheimer tested readers' reactions to formal and unnecessarily complex language. Applied Cognitive Psychology published his research with the only amusing title I've come across in a peer-reviewed journal: Consequences of erudite vernacular utilized irrespective of necessity: Problems with using long words needlessly.
Oppenheimer's conclusion? Most readers judge writers who use fancy words to be less convincing and less intelligent, not more. Ouch.