Agreed, but adding in other mechanics that are a valid alternative to waging war, even with the world conquest goal in mind might bring enough variety so you're at least not all that burned out with repetitive battle after battle by the time you actually take on the rest of the map.
Seems legit. And I don't really see why this wasn't put in as an anti-snowballing mechanic when player independent snowballing was such a large issue during EA. This could just as well be a general rule. The "coalition" of course would then have to react appropriately, so you don't get however many smaller armies running into the massive doomstack without any hope, and the coalition triggering proportions would need to be big enough to give a realistic chance.
The world conquest goal is always an option and used in a lot of games. The problem is that it is the only viable option in Bannerlord, because there is not much to do aside from this in late game. Things like tournaments, quests, trade, characters development, etc, mostly disappear in late game. Yes, all these things are still present in late game, but there is not any incentive for doing these things in late game.
If you compare Bannerlord with CK3, it is not like if CK3 would have tons of features, but paradox games know how to fully take advantages of the few available features. In CK3 game you have a progression feeling, but you are constantly dealing with leveling up, arrange marriages, caring about having kids, finding replacement for dead court members, etc. The whole CK3’s fun moves around death&aging, and this game would be a huge garbage if aging&death pace would be as slow as it is in Bannerlord.
Devs have probably invested a huge effort on making aging&death feature works, and it is currently totally wasted because people rarely play with their kids, because the game gets really boring at late game and people start a new campaign. If we would have to deal with leveling up, getting money, finding new companions, arranging new marriages, having new kids, improving relationships with other clans, finding equipment for companions, leveling up new companions, etc, etc in our current campaign, we would not feel the need for starting a new one. What is currently happening is that the game is just forcing us to play endless wars while leaving aside all the other game features in late game, and these features are which make feel the early/mid game pretty so damn fun.
Bannerlord should learn from CK3 how to fully take advantage of all the game’s features in late game, while keeping a progression feeling for the player. It is actually not hard to achieve in Bannerlord, we currently have clan tier, money, items and owned fiefs which we keep after main character death... What we are currently missing, is having to face the MC death (with all consequences like having to marrying again, finding new companions, leveling up, etc, etc) more often.