I would like to be able to change dimension settings on an existing dimension from within the Properties dialog.

AutoCAD allows this, and it is incredibly handy. I like the ability to turn extension lines on/off, or to change terminator type after placement. There are other settings as well, but I use those two most often (along with the ability to "flip arrowheads" which would be nice to have as well).

Currently, changing anything about the style of an existing dimension requires us to Match the dimension style (assuming that even works correctly), set that to active, edit that actual dimension style in the dialog, and use the Change Dimension tool. Aside from the obvious clumsiness of this approach, it also carries the risk that whomever is making the edits could accidentally Save these changes to the actual dimension style, messing up other existing dimensions which did not need adjustment.

Changing dimension settings on a per-dimension basis in the Properties dialog would avoid this pitfall and make dimension changes far simpler.