Now you might say one of 2 thing. "But we already had garrisons!" or "Lets just have guild housing for the "MMO" game!"
Here are my responses. Garrisons are not player housing by a mile. and 2, Who says player housing has to be solo only? Did anyone play games like Runescape? where you could have mini games and even dungeons inside of your home and invite others in for parties? (not to mention demon butlers!) Ark and conan exiles you can invite others in for RP or as a base of operation.
Player housing would be content in the game that would not only bring us back to older content, but last up through new content and even last through future expansions, instead of being an expansion feature and being left behind like the farm.
The only issue i can think of, is how you would build the base of the house, because we would have 3 options;
1; The home is pre-built but you can decorate it (almost like skyrim but you can add in what ever furniture you want)
2; You can build it in spaces / rooms and add upstairs and downstairs. (Like in Runescape)
3; You have full control of building it like in Ark or Conan exiles.
The game should allow us to have a choice between various areas of the game. Like choosing to live in tanaris, winterspring, mulgore, etc. But it would just be a template and it would ne instance. Like the homes in runescape. That you would need to venture to the portal of the designated zone to enter. (This would also allow for gathering hubs for players who wish to form parties.)
Now for the content.
Up untill now I have been using runescape alot as an example, one thing I do not want from runescape, however, is the building profession grind. While I am not fully opposed to having a profession for creating and selling various furniture, and it would allow for more ingame trading between people. I think other ways of collecting furniture, or even the recipes to create the furniture should remain in the world, pvp and in PVP.. (and maybe pet battles for those people too)
There can be standard tables and chairs, but themed furniture and decor is what most people want.
How about we return to WoD to find and collect Orcish tables, banners, fur rugs?
Or gnomergan for gnomish decor?
Even northrend for the more northern, hunting lodge themed decor sets, or even vrykrul themed?
Mulgore and highmountain for tauren totems.
There are LOADS of possibilities with player housing that can be a reward for many current and even new forms of content that can bring us back to older expacs and even feed into newer expacs so it will always be relevant.
And the best part, unlike garrisons, these would be cosmetic only, and not mandatory for raiding