I see a lot of people writing off 1337. Surely other people enjoyed it? Trying to resuscitate the Byzantines has always been really fun for me.
1) It's only 116 years of historical medieval era and even with later gameplay enabled the game has no systems to enable transition into early modern era. Hell, it starts to fail in 14th century because it's about the time firearms started revolutionizing European warfare. Firearms had enormous importance for Ottoman expansion. CK is also utterly unable ofc to model exploration era.
2) People simply like to play far longer than 100 years, for me campaign not lasting at least 200 is very inconplete
3) In 1337 everything (infrastructure, tech etc) is established limiting your own ability to develop the world
4) 1337 is becoming geopolitically close to 1444 and people who played eu4 like me prefer more exotic times, not similar political order like their countless eu4 campaigns
5) 1337 bypasses crusades, Byzantine power, caliphates, mongol invasion and most of paganism.
IMO 1081 is better start date than 1066, even weakened Byzantium is still powerful and it has much more interesting starting position - besides, if somebody wants really mighty Byzantium, you'd always have 867 (and 936?). Also Jerusalem controlled by Seljuks instead of Fatimids (and weakened Byzantium) make for significantly more historical crusades. Also slightly weaker HRE. I honestly think 1066 is mostly due to memetic anglocentrism.
936 is a brilliant start date and I hope is in available on release date. 867, 936 and 1066 (1081

) would make me satisfied.
It's be cool if we had some crusades start date after forming crusader kingdoms (early after first crusades or in Saladin era) and between 1204 and 1220, when Byzantium is crushed and Mongols are coming.