I like how the units in this game have passive abilities, but some of them I just don't agree with. Spearman Wall The spear's advantage is its range, allowing you to hit your opponent before his shorter range weapon is in range. Originally, I would have just asked that the spear's passive ability be that in melee the spearman always attacks first, but I found it difficult to make that work game-wise in my head. Now I would simply suggest that when defending in melee that spearmen have increased defense. Knight's Charge You're asking a lot for knights to only be able to activate their passive damage when they expend all of their movement points in just one direction. Wait, it's only tied to movement points? That's... um... but corners. Please make it to where Knights gain damage the more movement points they spend without turning a corner. Just not having to expend all of their points. Spearmen more expensive than Swordsmen. It bothers me that developers always seem to have the misconception that spears are more expensive than swords. Spears use less metal and are easier to craft than swords, although it seems as though the black smiths in this game are for some reason making the shaft out of metal so that would explain their expense. Make the spear's rod out of wood please and make the spearmen the cheap unit. I know this isn't a passive ability but I still want this change. Regardless, I am still looking forward to the progression of this game and wish it good fortune on the market.
The issue I see with your first two points is that the developers want each unit to have a critical effect which triggers under certain conditions. For the spearman, they could make it to where they critical when counter attacking, but then smart players would just never attack them, making spearmen useless except for choke points. As for the knight, I believe they said in a past stream that all the movement must be in one direction. I suppose they could lower the amount of movement needed and also lower the critical effect, but then it becomes too easy to trigger. The reason spearmen are more expensive than soldiers is not because of the weapon construction, but because of in-game utility. Spearmen can counter more units, including knights. Soldiers can only counter archers.
I agree spearmen should be the cheapest unit, they are easy to make and easy to use (compared to a sword) Spearmen should be cheap, expendable but cost effective versus mounted units. Swordsmen more expensive but slaughter infantry and better on the attack. Alas I doubt any major changing of unit roles will happen now so for your own sake just imagine the spearmen are elite disciplined soldiers rather than your typical rushed into service peasants who are probably defending your towns instead.
The reason they make spearman more expensive that soldiers is that if they where a cheaper price than soldiers, soldiers would become an invalid and unused troop, hence wasted developement time. Aswell as spearmans larger utility range.
I think the idea with spearmen is to make them a specialized defensive unit. It's not literally meant to represent a single spearman vs. a single swordsman, but rather a group of swordsmen/spearmen, as you can tell from the little battle animation whenever they fight. If you have an army of spearmen, they're going to be most effective when they're standing in a line, since the enemy can't penetrate through them. Hence the passive ability. As for why they're more expensive, it could be just a scaling thing -- they're 200 gold instead of 100 but they have 2x better combat stats. Another possibility is, one thing I've heard game devs do in other games (like league of legends) is encourage aggressive rather than defensive play. This helps the game progress & encourages people to make plays rather than just setting up defensively and sitting around. Since spearmen are intended to be used defensively, they increase their cost so that a player's first instinct is to play more aggressively with swordsmen. Another thing is that the higher cost indicates that the spearmen are just specialized -- they're for defending, and if you're not defending, don't build spearmen. The higher cost just hints to players that they should think twice before purchasing spearmen, so swordsmen will be the go-to unit to buy when you don't know what else to buy.