As they exist now, runes offer attribute increases and a bonus special effect for wearing a complete set of six. In many cases, that special bonus dictates which runes players use, In many cases, that special bonus dictates which runes players use, even if they would prefer different attributes . After we launch Guild Wars 2: Secrets of the Obscure, rune sets will continue to provide attributes like they do now, but the special combat effects will be transitioned to relics.
https://www.guildwars2.com/en/news/relics-bring-new-equipment-to-guild-wars-2-secrets-of-the-obscure/