I've been asking for a new debuff for BRD for ages, so I'm really happy about Pining Nocture. About the not stacking with Addle... I dunno, it might make sense. A fully well-geared RDM using that JA enhancing the next debuff can bring Addle to really high levels, perhaps too high. Having this stack with Pining Nocture might be a bit too overpowered...
I hope Pining Nocturne will be an element different from Fire, that way you'll be able to put it on NMs that are immune to fire (and hence to Addle).

Only thing that really bothers me atm is the fact that you can't overwrite Pining Nocturne with another Pining Nocturne, i.e. making us unable to refresh it before it expires. Really hope they have changed that in the patch that will go live tonight, or that they will change it in the future.