The emotions are a power source and will power is the trigger.
The lanterns are the power source the emotions (will, greed, rage, love, hope, fear, etc.) are the triggers or the on switches. If the rings aren't charged in the lanterns then the rings won't work. Therefore, it doesn't matter what your emotion is because if you have no power the rings won't work.
Lantern equals the gas to run the car.
Emotion equals the key to start it.
Can't start a car with no gas and you can't start a car without turning it on.
i was totally dissapointed in this episode. it seemed to be more for the yucks than seriousness Larfleeze didnt come off as a menace at all, but as a joke. i know you cant have dude killing people but come on!Snatching the fly around his stinkin butt to give to Hal and friends!?!? and freaking Hal got taken over way to easy for being the greatest GL of them all for me!nawww! i wasnt impressed but i did dig hal's orange lantern outfit! kinda look like ole skool wolverine's threads

t:
Well it's a filler episode used to show the passing of time between one episode and the next and advanced the main story a tad bit.
I don't feel that larfleeze was suppose to come off as menacing. Avarice or greed is an emotion that can take over anyone. Obviously it was an homage to LOTR's gollum which was cool to me and we already have enough bad/evil guys with power rings.
The reason I felt Hal was taken over so easily is because as you say he is the greatest GL of them all...or at least for you. When you are held that high or want to be the best of something greed isn't too far behind. Just look at Anakin in Star Wars. Since he was a kid he was touted as the one that would bring balance and order. The greatest Jedi that would ever live. However, his buying into that prophecy and his own ambition turned into greed for more and more power in order to be the strongest and the best.
Where there is ambition and drive to succeed, greed is not far behind.....a very thin line sometimes my friend.
I also dug the orange outfit.