Most of them have back stories HM goes way back Sundering same goes with Shal'dorei. Both allied races focuses on antiquity while on the other hand LFD and VE pushes the story to the future and mostly spacey/outworldy/futuristic.
on the other hand Maghar orcs have their story in a back to the future treatment similar to the alliance counter part while DiD story is dealing with the past- reuniting DI as a whole, deal with Ragnaros ress, possible Grim Batol story arc, etc
Telogrus rift perhaps is just one of the dimension that was recently discovered and perhaps there are other more places as a wake of destruction left by the void. I firmly believe we will see more of their place and their design/architecture/aesthetics near future probably during N'Zoth/old gods/Void Lord chapter of BfA or future expansion and explore more void consumed planet/places. Who knows what world they could discover where void plants and trees which learned to survive and adapt in the coldness and darkness similar to the depths or abyss down the ocean.
Looking forward to Forasken+Blood elven mix for their architecture. light blue -pink flames from candles and chandeliers or lanterns. Ashen gray woodworks. Navy blue to Deep purple paint job.