Quoted from meSz:Interesting that the rule sheet states "Shoot DWARF target with upper flipper" so maybe we're starting to see specifics to the upper flipper!
There is also the "Hit travelling drop target before it's gone" rule. The rule doesn't require you to use the upper flipper then, but if the timer is running out you might very well find yourself in a situation where the upper flipper can save the day. Seems like a satisfying thing to nail in desperation at the last second, when you really, really want that extra ball.