The single best way to improve usability of Wikipedia would be to scale back the use of jargon.
if you look at early discussions in those days they were usually held in plain English, with very little jargon. I've tried to keep up that style, but it is now quite rare.
I don't see why this should be. Our policies have perfectly good English language names, "Neutral point of view", "What Wikipedia is Not", "Verifiability", and so on. There's absolutely no need to replace these English phrases with gobbledygook.
We have no strictures against this exclusive practice, mainly because it was seen as obviously undesirable in the early days. But communities inevitably acquire exclusive practices as they develop--it's seen as one way to identify yourself to other people as a member of the "in" group. And so now when I discuss matters on Wikipedia talk pages even I, an editor since 2004, find myself shuddering inwardly at the impact of all the alphabet soup. If the damage this practice does to the openness of the community were more widely recognised it would be possible for us to agree to scale it back, but it just isn't on the map.
in all conscience I cannot see anything wrong with our user interface. It's exemplary, and its having changed so little in all this time is good evidence of that. If we were to try to emulate monstrosities like the ever-changing Facebook it would be a step backwards from our unflinching commitment to a good, clean, simple interface.