The difference is WoW is dropping a lot of subs even though it's not the end of a expansion. 10+ months of the same raid would be horrible, especially with all the new MMOs coming out soon. The Elder Scrolls already have an insane amount of fans in the world, a lot of them also playing WoW. Blizzard need to release something around the release, just like they normally do when other MMOs are being released.