I assure you my hardware is well beyond what is needed for a TW game, the typeface is small and a simple google search will tell you others are complaining as well. I'm sure there are harder factions, and I think I'll try the "warrior monks" one next (forgot the name). But seriously, that thing where the AI had a fullstack of Yari Samurai on turn 7 is not possible. I'm no Shogun 2 expert but don't Samurai units require 2 seasons to recruit? Even if you have one extra slot per province form an event you got at turn 1 and you have two provinces, that's still a maximum of 5 units per 10 turns. Unless they start with 10 units, but that'd just be silly.
The AR mechanic is broken and I refuse to accept your logic "it's clearly imbalanced so don't use it and stop complaining". I use it because it saves time, I don't have a lot of hours to put into gaming. I'd rather avoid as many loading screens and rearanging troops and then a 2 minute march on the fastest speed, then breaking enemy morale, mopping up the retreating stacks etc. That's 10 minutes I'd rather not spend unless me personally leading the battle meant the difference between victory and defeat.
RTW was too easy but not because your units never died, it was because the economy got too out of control too quickly if you knew which provinces to take. Egypt disagrees with your one stack that never takes casualties.
You don't run out of population to recruit in the big cities but it does slow down province growth, especially in the less fertile and poor barbarian provinces. Have you given factions like Scythia or Numidia a try? Making two full stacks out of their basic provinces sets them back to the stone age.
The retraining method is not realistic. You can't outfit and recruit raw peasants into a unit of 4 exp bowmen. Getting the necessary muscles and training to be an effective archer takes years. It's especially absurd for monks and samurai - camping in the countryside makes them magically replenish? That does not make sense. Returning to a city and spending money on retraining does make sense and it worked just fine for older TW titles, this was an unecessary change. Like the removal of hotseat, modding, forts, watchtowers and the addition of skill trees for generals.
Bookmarks