Yes, endless wars is by far the most annoying thing in the game currently. As king, or vassal, most of the time you do not have a single day to do anything different to fight battles (if you care about your kingdom keeping its fiefs). I barely can find time to get a new wife if I lost her, or to try to get a new kid, to try to recruit a new specific clan, or to go to a far away town to buy some horses. I know that we do not have much late game content currently but the current war pace does not even allow us to enjoy the few other features we have currently, different to endless wars.
Seriously, getting at least 10-15 days of total peace would be pretty much appreciated but it rarely happens.
Concerning the game lacking late game content, while it is true, for me the biggest issue currently is related to a poor balancing. We cannot enjoy the aging&death feature because characters take ages for dying, and same for getting the new kids ready. Aging&death is the most wasted feature we have currently for sure. Then we have a poorly balanced leveling system, and increasing some companions’ skills is insanely hard. Then we have smithing, which is not enjoyable at all for me because it is broken, and it feels like cheating the game.
If we think about battles, once you get some high tier archers, the game is over and we are able to facerolling the poor AI.
Equipment is ridiculously expensive and getting some fighter companions, buy expensive equipment for them and enjoy use them as bodyguards is impossible (if you do not want to cheat the game with smithing), and getting a regular Empire recruit is always cheaper and easier, because after some few days we can upgrade them to legionaries who perform much better than companions in battles due to equipment. So yes, while we need more end game content, the biggest problem in my view is the current content being totally wasted due to balancing issues.