With weapons so accurate and really stubborn commanders who refused to take a glance across the great big pond, it's no wonder why tactics quickly went from linear Gustavus/Napoleonic tactics to something else (I phrased my sentence that way for what will be apparent soon), however it never made sense to me why commanders on both sides never considered replacing these outdated tactics with open order, free command tactics that would use open or concealed cover, aimed fire, and rapid movement to apply pressure on the opposing side.
Because they did. Sadly, u/elos_ has since deleted their account, but that answer makes it clear they did already use pretty much everything you named.
really stubborn commanders who refused to take a glance across the great big pond
Bonus addressing of this point in this answer by u/vonadler, with two bonus answers plus discussion linked in that post.