You're missing the point. The thing with garrisons in WoW was no one could visit your one unless you were in the same party. Unless you did that you only ever saw npcs so the area quickly felt like anything but alive. In FFXIV you can see other players in the residential district without needing to even know them at all. I know players who made friends with their neighbours and even joined their fc. That being said you don't usually see many players because most of the time they're elsewhere in the game doing dungeons, etc.
As for wards being half empty because of house flippers, my impression is that most realms aren't quite as bad as this. Moogle certainly is not. There is a housing problem across all servers but it can manifest differently due to things like population, how old the server is, server economy and what region it is intended for.
Yea all that is seriously cool but my experience in WoW has very much coloured my view on instanced housing. I don't mean like apartments, I mean when the outside and inside are both instanced. I can most certainly see the great deal of advantages it can provide, but there are some downsides as well.
Garrisons in WoW greatly isolated people from the game to the point that major hubs looked more noticeably empty than before. Part of this was due to the role they played in the game itself but another big part was the fact that they were instanced (actually phased, which is similar to instancing). It was ironic that a huge amount of players were all in the same location in the game but never saw each other because they were in different instances. It was such a huge disaster that garrisons got a massive amount of hate and an enormous amount of players are entirely against any sort of housing to be brought into the game again.
I'm not saying I don't want to see any instanced housing similar to Wildstar or WoW, but I have seen it go horribly wrong so I would be very concerned if SE considered doing similar.