I don't have a better answer, so I'll agree that some pronominals are used to either intensify or emphasize an action.
I'm not sure of how I would translate the nuances here, but maybe some more examples would help...
·El albañil cayó del tercer piso. -> An objective description of the fall.
·El albañil se cayó del tercer piso. -> Underlining it was nobody's fault, but something beyond anyone's control.
·Cada año vamos a la playa. -> Telling about a custom.
·Cada año nos vamos a la playa. -> Underlining the fact that we leave everything behind.
·Comió toda la sopa. -> Simple fact.
·Se comió toda la sopa. -> Emphasis on someone's eating it all up.
·El abuelo murió en su casa. -> Telling what happened.
·El abuelo se murió en su casa. -> No one could have done something about it.