What the variables provide you is outstanding, however, I think managing the variables would be much easier if the UI was redesigned. I don’t have immediate suggestions, but just putting it out there for discussion. Many shortcuts, bulk tools, copy between projects, etc. could be very useful in much the same way TeamCity provides Copy/Move between build configurations.
Lots of room here for developer-focused and release-management position style features. I find variable management the slowest part of setting up a new deployment project in Octopus.