ArenaNet originates as SOME of the original WoW developers. So basically they "KNOW THE LIST"
By list, I mean, the original X-pac rotation of WoW.
Take close look at Guild Wars 2.
The one thing I notice is that unlike other failed MMORPGs, ArenaNet seem intent on taking and coping WoW related features.
Notice the similarities between GW2 and Cataclysm(Sea x-pac)
Both are the rise of Underwater gameplay, and a lead Dragon as the big bad guy.
Even more closer examination of the two, you can see GW2 copy lore from WoW.
Example : The new plant race Sylvari
They are very similar (in concept) to the Night Elfs. A race that seem very connected to Plants. Well thats common in all DnD elf races right?
But the main similarity between the two, is that they both have a enemy known as the NIGHTMARE who is corrupting their own racial members. Isnt that similar to the Nightmare in the Emerald Dream?