Yes, there is a lot of work needed to make the processing rules UI more user-friendly. I share many of the same points of feedback you've listed above.
I also would love to be able to delete context data variables from the list once I know they are no longer being sent in current requests.
Also, when editing a rule, I hate that you can only insert new actions at the bottom and cannot drag and drop them to where you'd like within the current rule.
Many, many more.
I had a meeting with some Adobe product folks today, and I am cautiously optimistic that they are paying some attention to feedback about processing rules right now. Don't give up hope yet!