I have worked in and around Scientists for almost 20 years. The primary role of these scientists is to conduct research in their chosen field. However, they also have a secondary role, which is to educate the broader public about the importance of science and the relevance of their particular field of study.
When asked to write content for websites, scientists often ignore many of their target audiences and write specifically for their peers - other scientists in the same field.
A conversation that web team members often have with scientists is:
Web team: "This content is hard to read and even harder to comprehend."
Scientist: "You want me to dumb it down?"
I have always had problems with the phrase "dumbing down". Scientists sometimes assume that they are more intelligent than their audiences and that attempting to communicate clearly with anyone outside their profession is beneath them.
The reality is that writing clearly is a very specific skill, and definitely not a simple process of "dumbing down".
The answer I have always wanted to give to these people is:
"No, I don't want you to dumb it down. I would like you to write more intelligently. I'd like you to understand who you are communicating to, develop some empathy with these audiences and attempt to communicate clearly with these people."
Unfortunately, it is very hard to measure whether content is well written or not. While readability tests can be used to help authors determine "how readable their content is", these tools are based on algorithm and do not really address the main objective - clear communication.
Some more information on Readability: