In tons of singleplayer mods, improvements to the AI have been made to make them less retarded. For example, the Eagle and the Radiant Cross mod I was just playing.
They have 15th century pikemen there with 400(!) length pikes and they are actually one of the best melee units in the game. The AI switches to a back up sword when an enemy gets within a certain range and switches back to the pike when they get some more room. Combined with them using square formations, groups of pikemen supporting eachother actually turn into a deadly killing machine, like they should be, instead of a bunch of retards glancing while the enemy shielders slaughter them.
I imagine this would also work for lancers and hoplites, having them switch to their swing weapon when fighting up close. AI improvements like these and being able to use formations would propel this game mode into so much more awesomeness and would go a long way into reducing frustrations about the AI sucking at using certain weapons. I think these scripts for the AI are pretty much freely available.
If your cav has sharpshooters in front of them and inf a bit on the flank the only way to make proper charge is lead them... 50 xbowers shooting at you quite often ends in your death 
Hold F1, put the little flag where you want them to go, release, watch as your infantry advances with you behind them. I had the same problem until Zlisch pointed this out, always just used the minimap when commanding in singleplayer.
