One shouldn't compare the WoW Garrison to player housing from other games which have a different development team, a different engine, a different setting, a different system and so forth. It is TOO different.
I have tried several games which have housing but I haven't tried the Garrison, I can't form an opinion on it... even with all the info given. I need to walk through it on my own computer and try it out to say 'yeah, this is(n't) really fun/what I expected/what I wanted'.
I for one am glad Blizzard is slowly starting to pave the road towards possible player housing and that they are testing different things first rather than smack a house down somewhere and fail at executing it because they don't have the experience for it or the right system. Old engine is old, no matter that they update it with each expansion; stop forgetting that.
Guild housing isn't my cup of tea. The only time I witnessed it personally was in FF14 (through a friend) and even then it felt like the members didn't have much of a hand in having the house... other than having chipped in to get that ridiculous amount of in-game money to buy a decently sized plot. It was bought, the guild master decorated and... that was that. Guild meetings? Only the guild masters and the officers would meet to discuss things and even then they would not use that damn house. They spoke over a linkshell (chat channel) so they could at the same time tend to their own business. It felt useless for the other members.
Player housing can be turned into guild housing if one were to desire it; there is no need to make a guild specific option. The WoWGarrisons and the housing in Wildstar allow people to visit, come around, poke about and what not. In WoWGarrisons it is through a party/raid and in Wildstar it is by assigning other people as a neighbor (or even a roomie). It is the same thing for a different kind of game option because seriously, the difference between the two is still pretty big. Also something people shouldn't forget.