Dark side users connect to the force through passion instead of from focus like the Jedi. The reason is because passion and emotion are very strong connectors to the force. The Jedi choose to connect to the force through focus instead because passions can lead to the dark side.
What if someone used only the positive aspects of passion to reach out to the force? Imagine instead of channeling your hatred for an enemy you wish to destroy, you immerse yourself in your deep feelings of love for someone you wish to defend and Channel that love in a defensive way - "the only way to save the innocent is to defeat my enemy"
What is stopping a light sided force user from channeling feelings of love and mercy and justice in the same way a sith might channel hatred, but for selfless defence of the innocent rather than selfish aggression?
Wouldn't positive passion hold a strong connection to the force in a similar way that using the dark side connects to the force? Wouldn't this lead to a light side user gaining a similar (though perhaps less powerful) power boost without having to commit evil?
(For the sake of conversation, let's ignore the fact that holding such strong emotions at all could possibly lead to the darkside in the long run anyway. Although, I'm not sure that it necessarily would?)