if u wanna play violently at ur guitar. start playing flamecio.
rasgueado, is what i suggest u start practicing to give ur guitar a more violent and non-slapback sound.
so just because u cant get angry with ur guitar doesnt mean u have to quit. just look at differnt genre's and which ever is right for u to play/listen to then play it.
and if ur gonna whine that u only like metal then mix the two genre's together. for a more enjoyable playing experince