I don't like any of the two extremes that you are describing. Of course the game must not be "railroaded" because then it wold be better just to watch a history video. But many players, I included, prefer that the world that we are playing remains "recognisable" in historical terms. So, yes, I like that outcomes are open and that you can change things, like make England raising to be a dominant power in 1500 or Spain remaining a dominant power after 1700, and so on. But I don't feel attracted to a game where Bourbonnais, Savoy and, Scotland are the dominant powers in Europe. Just Because I do not recognise that world, so my immersion in the game is lost. And I think that a majority of players feel the same.
Now, I understand if you prefer that way, and dominate Europe along the game playing Burgundy or Serbia. I suppose that there are room for both approaches, and you can always mod the game to your taste.