If you understand something, you can explain it simply using plain language. If you can't, then save it for your limited academic audiences. It's not only academics who do this, too. Activists at all levels are guilty of it, too, using terminology that is limited to their individual communities. It's true that more privileged people could bother to educate themselves in some cases, but not everyone has the ability or resources to do so. You should strive to be understandable as much as others should strive to understand.