If you get a high health one, you can use it to drain the stamina of Gigas, Brontos and Rexes as they all have very fast stamina drain, and since the Kapro has attacks that drain stamina, if they hit one of those they will basically have no stamina in no time. Just level health and attack, and have a decent saddle. They have little health, and those war machines have high damage. Though they are most likely a one time use, they will be of no use if they die before they hit anything.
I think the devs should add a command for singleplayers that makes it possible for the Kapro to grab creatures on it‘s own without attacking them, so the player can stand in front of him to knock the dinosaur out (as a command like you can activiate turret mode with the chalicotherium)