The line weights of Sketch lines and Dimension Leaders should be different, or at least changeable in the preferences.
Sketch Lines and Sketch Dimensions all appear to be the same width, or "weight." An extra line or lack thereof can often be overlooked due to being colinear with a dimension leader. And, in a somewhat complicated sketch, the thicket of dimension leaders and sketch/construction lines can get debilitatingly confusing.
Conclusion: The difference between Leaders and Lines should be more obvious.