The "boom and bust" cycle is pretty much working as intended, if one believes the numerous statements made to that effect by its Producer.
The population has been pretty stable, although you might not notice it if you don't pay attention to DPS queue times throughout any given day on North American servers.
Housing might seem like a wonderful way to encourage players to visit more. Housing in other games has always been more of a "it's available, I tried it out, I have many that I haven't visited since <MMO> lost popularity" for almost every MMO I've played that has housing. I have apartments and FC rooms in this game, and don't make a point of actually going to them even on a monthly basis. It's not the draw you think it might be.
I haven't found the Overworld in most MMOs to be all that exciting. At max level in WoW, you tend to visit only those places necessary for doing your dailies. In Rift, you only visit those places where Adventures lead you.
In GW2 you visit a few well-timed events. Those events are, essentially, the equivalent of FATEs, complete with a scheduled start and end time. They occur even if there are no people in the zone.
Puzzles are great as one-shots, and then you never do them again unless the game gives you something for completing them again. It's something to do, along with Vistas. There are jumping puzzles and sightseeing logs in FFXIV as well, just not rewards for doing them more than once.
GW2 has a problem with population. It seems stable because there are dedicated players who really enjoy the game, plus a smattering of come-and-go players who enter and leave without much fuss or bother. The people who still play it actively every day are familiar. The people (like me) who visit it once every two or three months make hardly a blip in the numbers logging in. This is why smaller population MMOs that have been around for a while don't seem to have that "boom or bust" cycle. There is no longer a reason for a "boom". Just a population that enjoys the game the way it is.