To Daelix:
»Historical accuracy« is indeed nonsense; I can only speak for myself, but what I'm criticizing is exactly what you speak of. I cannot play as Lübeck or Livonia — not in the sense of »religions.txt doesn't want me to«, I can fix that in five minutes. I cannot play as Lübeck or Livonia because Denmark, Sweden or the Empire comes around and kills me within twenty years, before I have a chance to mount any kind of defense. The Emperor is the worst offender — Heinrich IV should be dealing with Saxons and Swabians trying to grab his crown, and also with the Pope claiming the right to invest the Imperial bishops. Instead, he stomps Mecklenburg with 15000 soldiers in the first few weeks, and then some Italians maybe revolt a bit, I dunno. Compare the situation with Iberia, where all the kings are fighting with each other for their claims on Leon and Navarra and what not: this conflict was quite inevitable in 1066, even though it had not started yet. If you start a new game in 1066, I can guarantee you that the Iberian Christians will fight against each other, sooner or later; but there's the catch: I can't tell you when that will happen, or how it will end. I can't tell you whether the Muslims will invade Castille while they're busy grappling with León — and if they do, whether it will be a successful campaign. Can we agree that this is both historically plausible and dynamic, interesting gameplay?
If so, imagine if none of the kings had a claim on each other. Suddenly, the gameplay isn't as exciting anymore — because of a historical detail being misrepresented. Similarly, the Holy Roman Emperor being well-liked by nearly all of his German vassals leads to all kinds of silliness and imbalance, since he gets so many levies and has a lot of free time (the +20 opinion modifier for Elective succession doesn't help).
With regards to your suggestions: Yeah, I agree wholeheartedly. And frankly, that's all I got here. By the way, is anyone willing to mod such things for a few hands-off tests?
What you say about Crusader Kings II getting anywhere close to »historical accuracy« by letting all the empires run rampant, however, undermines your point. There is no such »wild randomness« in CK2; for example, I can guarantee you that Nubia will never survive past the 1070s, unless played by a human. I can also guarantee you that the Pomeranians will be conquered by the HRE using de-jure CBs, within thirty years of the start date, and they can do jack squat about that. I can't guarantee you that the HRE and France will emerge as the dominant nations in Europe, but there's usually nothing to be done about that if you, the player, won't interfere. I can guarantee you that a conflict like the Hundred Years' War (which you indirectly addressed) will never happen in CK2 if you start from 1066, because England can't defend Normandy or accumulate much territory in France, long-term speaking. Sure, they take Paris sometimes, but there's no »moment of truth« where everything hangs in the balance until a Joan of Arc comes to the rescue, or a Napoleon is beaten back out of Russia.
EDIT: You claim that it's easy to conquer everything as Lappland. Fine, but that's because Lappland is quite out of harm's way and has enough time to build itself a good starting position. Lübeck is de-jure Denmark, and borders the HRE, and also borders Mecklenburg who can gobble you up just as well. Compared to that, Pruthenia is easy because you can bite large chunks off everybody, including Poland. They're still in no position to challenge the HRE with allies (Hungary), though.
Also, what I completely forgot to mention is that I want the AI Pagans to have a sporting chance too — the player can always do better, but have you ever seen AI Lappland conquer Sweden?