Maybe I've sound like an elitist jerk, but the fact that history knowledge helps players in playing this game is an asset, not the burden.
And if you don't, you
learn things from those games, which is absolutely mindblowing. Hearts of Iron series can be actually used as educational tools and to be fair, they often contain more detailed knowledge on certain things then popular-history TV and computer programs.
But I guess I know what you mean and your suggestion was somehow adressed - certain events are getting changed into decisions known from EU3:IN - so you can actually see what you need to trigger the event beforehand.
So yes, the key to success is making game as deep as possible - and at the same time improve its accessability.