It doesn't matter how short this expansion cycle has been, it has everything to do with what little there has been to do this expansion that makes it seem dragged out. I think many players would be just fine with 1.5-2 year long expansions if we got constant content updates every 2-3 months. As long as we got new quests, new lore, new instances, on a regular basis then most people will be fine with it.

Prior to the SOO drought MoP had constant updates every 3 months. We alternated between new raid tiers, and new world events, zones, world bosses, and daily hubs. It was awesome and the game benefited from that.

Blizzard really needs to fix how their design teams are structured. They need to have the current expansion team focus on adding new content every 3 months with zero regard to what the next expansion team is doing. When the next expansion is finally ready they can wrap up the current expansion and move on into it smoothly.