The best points are never made in Plain English, if by "Plain English", we mean English that is merely easy to understand.
Rather, the best points are made simply and precisely -- describing a Single Thread of Thought, using terms that are not Overloaded within their domain. (Overloading means to assign more than one meaning to a word)
Good Jargon does precisely this. It is a 1-to-1 mapping between phrase and idea that is used to succinctly describe an empirical observation. We can overload words in the host language, but not in the domain of specific models. eg: "intensity" in physics (W.m^–2) vs "intensity" in Strength Training (percentage of 1 rep maximum).
Yet, people seem to have this aversion towards Jargon. One reason is because people Scorn what is foreign. And since Jargon is, by definition, specific to particular domain, if one is not familiar with that domain, the language used would obviously sound foreign.
But that doesn't explain most of the malaise we feel toward Jargon. Rather, I think it is because there are too many instances of Bad Jargon that are both phonetically and semantically similar to our conversational language. Phrases like ""Prior Art"" (patent law), and ""Over-the-top"" (cellular providers), mean completely different things from what we expect them to mean, yet they can easily be mixed into daily banter. ie: they intrude on the conversation, and seemingly attempt to feign us with "malicious" pretence.
Again, it is Bad Jargon that is the problem -- why the hell should those cable companies talk in their flowery language, I just want good signal on my iPhone dammit! (I do not own an iPhone). Bad Jargon feels like that cheating spouse whom you think you know, but turns around and surprises you with yet another "But you said you would!"
Or take another scenario. If a Physicist starts talking about the relationship between light "intensity" and "luminescence" (both which are examples of Good Jargon), I doubt anyone would accuse them of harbouring bad intentions. At worst, the person would merely be viewed as weird.
Unfortunately, the media loves to spin Good Jargon into Bad Jargon. When was the last time you heard of a newly discovered Obesity gene? (I hope it has been awhile, and if it was yesterday, you need to stop watching/reading the news) The media would rather have you believe that Gene X implies Obesity, rather than tell you that researchers discovered a 15% Heritability (not to be confused with Heredity, both examples of Good Jargon) between Gene X and Abdominal Lipid Deposition.
Of course, that leads us to the other, arguably more important point -- that there are highly technical scientific domains which demand that we respect Good Jargon. Moreover, these highly technical scientific domains affect our very existence (the Internet, Cancer, Terrorism measures, etc). The consequence of not becoming familiar with the Jargon is ignorance, and being stupid is obviously not a good way to go through life.
Yet it is exactly these fields which are often met with indifference, and in the words of Elie Wiesel,
"The opposite of love is not hate, it's indifference. The opposite of art is not ugliness, it's indifference. The opposite of faith is not heresy, it's indifference. And the opposite of life is not death, it's indifference."
It's the attitude that Jargon is "something beyond you" that should be avoided at all cost.
In that way, a Fear of Jargon can be a good thing. It is a good thing when coupled with self reflection -- the onset of honest inadequacy, and empowered discovery. Let's start teaching that is school for a change.