They're mainly for sharpshooters who wants to get a little pump on damage.
Personally I have both Con rings and Acc rings and I change them when in need of different situations. For example I use Con rings when PVP or walking through high dmg mobs and PLvling, whereas Acc rings for extra damage during Solo Lvling (bring buffer/tanker), Bossing or Farming.
You may use it in more situations you just have to figure out what you need in diff times n places.
Hope this helps. Goodluck