The trouble with determining causes of loss of players is part and parcel of any MMO however you cannot point a finger at one thing or another being the overwhelming factor. Humans are, in the end, fickle creatures by nature. Most would argue that the game's ease of play and no real tangible challenge outside of forcing you to play as a team in a select few dungeons, i.e. Coil or CT, has left some with a bad taste in their mouths. And it is a fact that the housing issue has caused a lot of misgivings as to the Dev Team's, Yoshida included, attention to their consumers. But then you have to look at things from another perspective. While it has been said a lot on the forums games are indeed moving forward with the times. Ease of access is paramount these days as people are not only competing with their daily lives due to economic up's and down's. Honestly I wouldn't mind some changes to certain things but I do not wish to log on to the very thing I use to unwind and to forget about my woes only to find it has become another "job".
Now as much as this has been ran into the ground I will give my honest opinion of the housing situation. While it is sad that peoples' expectations or hopes if you wish have been dashed let us take a step back and look at this from a calmer perspective. Other than gardening and owning your own private chocobo stable what is the purpose of housing other than it being purely cosmetic? It doesn't offer extra storage space as far as I am aware (don't own a house and for the foreseeable future don't intend to) nor does it offer any buffs. Now having said this we can determine three things.
1: You ultimately are spending Gil on a house that possibly will get better implementations in the future maybe even the expansion. We are not sitting on Yoshida's team nor do we even work in any of the various development departments. Who is to say what will become of this?
2: In the end you will still be using some form of currency to get the food for your chocobo. Whether this is fruits for dying, leveling makes no difference. Or in the case of planting these things yourself for your personal use or to sell or both you will be spending Gil or Allied Seals. Not to mention the upkeep of the stables, namely keeping them clean. Which if I recall correctly is 20,000g per broom.
3: If you are just wanting to decorate with more space just to "show off", and I don't mean that disrespectfully, you'll still perform this task whether it is now or later.
Ultimately whatever the population of players is not everyone is interested in personal housing. There will be a slow in the inevitable land grab and to top it off the prices will have bottomed out provided they don't change them SE side altogether first.
Now as to a general idea of why people are leaving, it is never as simple as a supposed botched patch. True it may play a part but there have to be more serious underlying reasons. Maybe they need to budget their finances and a game isn't within those plans. Maybe their job has become more demanding of their attention and they're too exhausted to be bothered to let anyone know. There are way too many variables. It's almost never the game that causes people to leave. If people are unhappy with the game, especially one they pay to play, they will be long gone most likely by the time they reach level cap for the first time. Sure they may make sure their fears aren't just due to boredom from leveling and check out end game to see if that is the case but no one is that stupid to spend money on something they don't want.
tl;dr: Don't try to reason things that cannot be reasoned. Just enjoy yourself as best you can and if it was a friend/s that left then wish them well in your heart and let it end there. No good came from dwelling. You'll make yourself miserable.