Another example are issue boards. They represent elegant use of a good infrastructure ­— it is all just a smart use of labels. It would be very complex feature without the use of labels.

Issue relations are meant to be the basic infrastructure to build on (at least that is how I meant it when I posted the original feature request). Just like the labels are just a binary relation between a issue and a "label", the relations should be just a ternary relation between two issues and a "label". Then you can build issue task lists on top of the relations like you've built issue boards on top of the labels.

We already have a very nice example of such tool and its great use: the Board, where labels are used to store metadata and the Board is built above this storage. Do the same with the relations -- simple metadata storage to build on.