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.

Simple relations: [Issue A]---(relation R)--->[Issue B], which is a ternary (A, B, R) relation in a database.

I see specific relations in a similar way as labels. If a "label" is a binary relation between a label and an issue, "relation" between issues would be ternary relation between two issues and a label (from different set than ordinary labels).