Currently if I select a data element from the pool it is just copies to the text field surrounded with %%. If for some reason I change my data element, I need to find all rules where I used it manuall and change it. If the element would be linked to the rule, a change in the data element name would be applied to all rules. One additional gain would be to be able to see where a data element is actually used.
To be able to see where something is used would also be a good feature for events, conditions, exceptions and actions based on the suggestion here: Reuse events, conditions, exceptions in rules