I have a save from the very beginning. Played Warband for like 3k hours straigth so i knew how to approach the game somehow.
Joined Sturgia, everything was still pretty balanced for the first 200 days. If it wasn't for me Sturgia would have been eliminated quickly. after i joined Sturgia as mercenary, the whole empire started to fall apart with western being the strongest. Khuzait started to steamroll. But wars were still slow progressing. When i was ready to create my own kingdom via main story, i guess it must have been V1.3. the whole empire got devided between all ohter factions but most went to khuzait ofc. The behaviour of declaring wars changed slightly with the patches but with the new beta 1.4.2 it's gone too crazy.
Now all Factions declare wars on enemies they can't even remotely handle (Sturgia declares war on Khuzait while they are on peace with everyone so very strong and will steamroll sturgia as soon as i let the game progress from this point). And besides that, everyone starts to declare war on anyone it's crazy. I won't continue this save for now since i know that now with this braindead behaviour of the factions they will get themselves eliminated in a matter of weeks ingame...
With the new System of voting for Wars it should be more likely that wars against too strong enemies will be downvoted/avoided in the firstplace by the NPC's.
For example, Sturgia was smart enough on my playthrough - after i saved their asses from khuzaits - to wait, and claim the spoils of war in the center territory and then stay calm for a while since khuzait had double the strength and battania was a little bit stronger (15kvs20k roughly). Vlandia lost many fiefs to battania and aserai, but then quickly stopped being at war on two fronts. But then 1.4.1 came out and it was a huge mess, so i tried beta 1.4.2 and many things got better (like defection of Lords that had a good relation with me etc. and some gameplay mechanics). But the insane behaviour of the Factions persists. No mentally healthy person would start a multi frontier war against 3 (or even 4 factions the last time i tested) wich are all severly stronger than themselves...
If a Faction becomes too weak because they lost on all fronts, well that was always happening previously in M&B and one or two factions get destroyed eventually soon. But now with this kind of insane aggressive behaviour, the game will be over very fast.
Well i had a big interest in claiming 3 Clans of Sturgia wich were my friends relation wise - to implement their fiefs into my kingdom to give me a kickstart. But after i noticed that they will only bring their fiefs if i am at war with them i decided to prey on the weakest faction at that point, that took a seriuos beating recently and just lick their wounds, Vlandia. But then the Patch kicked in and all the factions go crazy and everything gets messed up and factions start to dwindle in a very short time cuz they act like dog****. That makes me kinda prejudiced in this matter but still i think this behavior is not normal or good for the game.
Currently i always save and load to see how the factions react but since the patch it's insane how all the factions rush into war within one week like a madhouse and i won't play on since i know Khuzait will steamroll the whole map within a few months from that point. (one save that was before 1.4.2, i am watching until all factions are at war with eachother and reload to see if i can manipulate them or see a pattern).
I think many people have many opinions on thow factions should behave but in the end someone will always be disappointed. Still i hope that the devs aim on a long and slow paced game since the travel speed is also slower than in warband, if someone is starting to seige one of my few castles i sometimes don't even have 2 days until they crushed my defences. Keep the essence of the game wehre i can put in 1000+ hours and only have half the map after that, maybe some diplomacy system could help idk.
Don't give up and don't try to satisfy the masses. If you do that, the vanilla version will become a joke and will be for those 12 year olds with a super short ignition cord like the mate mentioned before. I loved the high dufficulty and slow pacing that warband had and would appreciate to keep this in bannerlord with more tools to make this even more immersive like dimplomacy options, the clan system heirs and so on. And don't forget to implement the things we had on warband already like freeing lords out of captivity including the related quests to do so for example and maybe bring back the fight your way out if you get caught sneaking into a town, that was awesome.
Now i stop, greetings.