UMLR — there are numerous places where associations between UML elements have only one, navigable role

In the specification there are numerous places where associations between UML elements have only one, navigable role. This seriously restricts the ability of derived properties that are added as part of a profile. Though most tool vendors implement bi-directional relationships for everything anyway, this doesn't help at all when you're trying to define the implementation of the derived property (i.e. tag), as part of a property. It is my belief that all associations in UML should be bi-directional to support a method of non-ambiguous definition. A couple of obvious examples are: 1. Navigating from a realizing relationship to a realized InformationFlow. 2. Navigating from an ActivityEdge to an Action via a Pin.