I'm quite happy with the 1444 start date.
And I disagree with the people that want the game to finish earlier than 1821.
What I would like is that the game has evolving mechanics that fit better into the 18th century.
Also conquer should be a lot slower. You shouldn't be able to conquer all Europe by 1600. Get rid of the snowball effect, which is one the worst things about PDX games, specially in EU4. I want too see large empires falling apart, not only AI large empires, but also when controlled by the player.
I find that it's not the snowball effect that is unhistorical.
It's the fact that you're not Sisyphus.
History has numerous amounts of examples of small starts blobbing out massively in short periods of time, like Mongols, Timurids, Seljuks, Alexander, etc.
History also shows that very, very few survive at their greatest extent past a century.
Most of them collapse from internal forces that rend them apart, whether it be exhausting the treasury, splitting the inheritance, claimant wars, and such. Or get get weakened by said forces until some new conquerer can snowball and meet the same fate.
The larger the nation gets, the stronger these internal fracturing mechanics get and the more time a nation spends dealing with it than expanding outwards further (or risk fracturing.)
In a lot of Paradox games however this Sisyphean struggle is never fully implemented. It's ignored so much that it becomes
easier to manage a realm the larger you get.
The need for player progression in a moderately sandbox game is the main sin here in these strategy games, present in here, Civ, Total War, and many other series. Devs design games under the assumption players never want to experience loss, and so it's all ever bigger external threats (Ming, Ottomans, Spain, Russia, etc) until there's not enough on the map to engage the player and we abandon the campaign centuries before the end date.
There's no real internal threats that keeps blobs (including the player's) churning up, down, or into and out of existence.