Provide the ability to flip clips within the bin rather than just the in the timeline using effects.
Often when I record footage on my action camera (DJI Osmo Action) the footage gets flipped 180 because the rotation is set to auto and it thinks it needs to be flipped. So when importing my clips into Premiere Pro, I can't rotate them until I bring the full flip into the timeline. This is difficult as i'm assembling and building my timeline.
Can i suggest just using the vertical flip effect. Select all the clips that need flipping and add the effect to it. You'll find it in the effects panel. You can even drag and drop the effect on clips in their bins.