The appearance inspector palette gives developers access to the full range of visual formatting available for a layout object, and styles give us an easy way to apply and change formatting that is standardized throughout a file. The formatting options currently provided by conditional formatting are comparatively weak. Using the full appearance palette would make it easier to create more sophisticated formatting for conditions. Using styles would extend the same productivity and quality improvements of style we already enjoy to conditional formatting; and, if conditional formatting does not gain access to the full appearance palette, styles would provide a second-hand way to access all the same tools for conditional formatting anyway.
The same effects can already be achieved by layering buttons, formatting each with the full appearance palette and access to styles, and conditionally displaying them using "Hide Object When" calculations. However, this creates more layout objects to be managed, stored, and transmitted over networks than would be necessary with more options for conditional formatting.