Why the hell is fodder able to counter elite units like Catpahracts, when the entire purpose of such units is that they are essentially invulnerable to fodder with no armor and wielding one handed weapons with no shields? Arrows likewise are absolutely ridiculous, as are missile weapons in general, to the point that there really is no point to ever get in melee. You will get swarmed by the cheapest and most garbage infantry swiftly and cut down regardless of how "good" your equipment is, and you're basically screwed as soon as you run out of ammo for your missile weapon of choice. Considering this is supposed to coexist with permadeath, the current lethality in bannerlord is ridiculous. And not just for a basic character level, but for gameplay as well. Being able to hack apart even the toughest units or characters with just a couple hits isn't fun, it's goddamn boring. There's no such thing as a lengthy good fight with the bots even on hard, as one of you will go down in just a couple hits despite wearing armor that should render you impregnable to most basic weapons.
This is pretty much what killed SP for me.
I can look past the hollow and boring village/town/castle scenes. (They're all pretty much ghost-towns)
I can ignore the one-dimensional quests and vapid lifeless dialogue.
I can even tolerate the lack of kingdom management and monarch options.
Why? Because it's a sandbox game and I can use my imagination to fill in any blanks in the game's setting, atmosphere, or "story".
But I can't use use my imagination to make flawed game mechanics go away.
When the actual gameplay (combat, battles) doesn't function in a proper or fun way, then I lose my desire to play.
Everything mentioned above by @Wyzilla
is why the combat in SP feels restrictive and promotes passive gameplay.
also brought up a great point about trash units being able to go blow for blow with elite units. I've always felt there was too much parity between all the troop types in Bannerlord. Aside from a few top-tier ranged units that stand out simply because they're obscenely broken and OP, there is little to no distinction between the other units in the game's roster -besides appearance/cosmetics. This applies to both different tier troops and different troops for each faction. They're all the same in terms of their functionality and ability.
Not only does this hurt the game's variety and the uniqueness, but as @Wyzilla
pointed out, it makes going the extra mile for elite troops moot, because at the end of the day there's not much separating them from mid-tier common units.
Warband had such vibrant flavor because there was a real distinction between low-tier fodder troops and a faction's elite-level units. It felt good to acquire t4 and t5 units because they had the skills and equipment to make themselves actually stand out form the rest of the common rabble. It made the player appreciate these top-tier units because while expensive, they were worth their weight in denars. Having an appropriate and noticeable upward scaling between each troop tier gave the player an incentive to upgrade their army to be the best it could possibly be.
In addition, each faction had distinctly different strengths, weaknesses, and playstyles -which greatly added to the fun of Warband. For example, Nords and Sarranids have very distinct troops with vastly different skillsets from one another. If you tried to play with Sarranid troops the exact same way you used Nord troops, you probably be in for a much more difficult time. These differences added to Warband's fun and gave the game an imaginative unique flavor.