“Dropped” status for individual actions is coming up in the next releases of OmniFocus (for Mac and iOS). If you’re interested, and willing to run test builds, please sign up to help test!
This feature opens up workflows in lots of OmniFocus systems — most notably the ability to skip an instance of a repeating action.
Let us know how it goes! You can choose Contact Omni from the Help menu, or post to the Slack group in the #omnifocus channel.