The action cards aren't useless... I don't understand that logic at all.
The attack action cards have a lot of advantages over basic melee attack, like considerably more damage, ignoring soak, extra attacks each round. The action cards really define a character in combat and gives him a lot of options. You could cut them, but they are certainly powerful.
They are not too powerful though and they shouldn't be. But they do give a lot of different advantages and the way some cards can interact allows for some very brutal combos.