I understand that the despotate did not possess the entirety of the in-game province of Epirus in the 1444 start, but 100% historically accurate borders will never be possible given the limitations the game has in regards to provinces. It's impossible to represent every historic nation that ever existed in the timeframe of the game without making ludicrous changes to the borders. For instance a nation of Monaco would be silly since the country is extremely small. Making a new province of Monaco thus wouldn't really serve much of a purpose.
However, at 1444, the despotate held about 60-70% of what the game currently has as the province of Epirus - so the estimation of "much" smaller isn't particularly accurate. And even if that is the case, why is it such a problem? Nobody really is complaining about Albania holding more territory than it did historically in 1444, nor about the fact many tiny German or Italian states are part of provinces/nations they didn't belong to.
Furthermore, at the time, Epirus was, in fact, bigger than countries that are already represented in the game, e.g. Ragusa or Lucca.
Having Epirus be a starting tag for 1444 would be much more historically accurate than having it be completely in the hands of the Ottomans.
BTW, I'm using this map for reference:
http://www.globalsecurity.org/military/world/europe/images/map-eu-se-1444.jpg
"Porting" this approximately onto the in-game Epirus (older version map, but the province in question still is the same):
http://i.imgur.com/uyYng5L.png
Doesn't look like that much of a difference to me. Note that Corfu is a lot bigger on the game map as well.