Sure. That works, of course. Horse archers die in instants when i play Empire with emphasis on elite cataphracts. What if you're doing a playthrough with emphasis on footmen and crossbowmen, with the occasional horse archer skirmishing force? Also, even if I decide to funnel those troops myself with a smaller force and a shield, why does my shield arm drops whenever I issue a simple order? Does that make ANY sense to you?
And it's not the same with Battania, of course. Sometimes they just have a single counter to HA: staying on a hill and peppering them with arrows. Different tactic, same issue: even if I'm behind the first line I'll definitely get some flak when I'm issuing the simplest of orders. And my shield arm will drop, of course. That is my issue, did you read the post in its entirety?
Also also: let's be honest. Few people play this game standing behind two lines. Most people, I'm quite sure, usually run amok with their cavalry. Hence the title, mount&blade. It's not yell&sit. Still, if you want to play that way it should be more than playable, fun, engaging and the like. It should be approachable from many different angles - yet the issue of giving orders = losing time and being completely vulnerable for no reason exists nonetheless.