I love Freehand because it's like a blank sheet of paper: I can draw wherever I want. I use it a lot for brainstorming. It will usually result that my thoughts I not arranged in a left-to-right order.
The Walkthroughs feature look neat but I can't use it properly this way as I should reorder all the content in order to make the Walkthrough work as expected.
Sometimes it's just a lot of overhead, other times the left to right order would be just inappropriate (e.g. I want to refer back to an earlier frame in my presentation or my content is arranged in columns like in a newspaper).
It would be great if I could rearrange my Walkthrough frames in any order.
I look at Walkthroughs as a presentation layer of my Freehand. With this view, it's even possible that I would create a different walkthrough for a different presentation. See PowerPoint, Google Slides or Prezi: they all support reordering your slides.