I for one would love to see player housing come to ESO, but it must be done right. I am a huge Skyrim fan and would using housing from Skyrim as the model for my suggestions.
1. Allow for multiple different types of houses/estates- perhaps based off class. My main is a mage. I really want to be able to build my own mage tower.
2. Allow for further customization based off of race- perhaps architecture, but at least through banners and flags etc. I want a large AD flag on my tower.
3. Allow for separate rooms with differing functions, like in Skyrim. Have a forge in the basement with crafting stations and storage room for mats. Include armor stands and display boxes. Allow your personal forge a unique selectable buff like the stations in the wilds have.
Along with a forge a library, Kitchen, Bedroom, Bathhouse, Magic study, Trophy room, employable guards, farm land, livestock etc...
A. The library could display all the books that you have read on your adventures, each readable again. Perhaps it could allow you to collect sets for unique buffs or skill improvements.
B. The Kitchen obviously would allow you to cook and provide storage for your food materials.
C. Bathhouse could allow you to bathe and perhaps increase the rate at which you gain experience in your skill lines (cleanliness buff

)
D. Trophy Room could display your most potent opponents- Deadra, dragons, bears etc.
E. Study could have an enchanting table with mat storage a unique buff for using it.
F. Bedroom which when used at night gives you a well rested experience bonus.
4. Allow this housing to be used anywhere outside city limits. Want your tower in the middle of the forest? Fine! Want it at the foot of a volcano, okay! Allow friends to see the location of your home and allow unwelcome guests the chance to break in and steal something. Hire guards to defend your home while you are away.
5. Allow the professions to make craftable items for the home such as beds for carpentry, drapes for clothing, bars on the windows for metalworking, seeds for provisioning etc...
6. Allow the home to be subject to the environment and creatures around it. If you build it next to deadra have them attack the home and perhaps set fire to a wing. Have traders come by and offer to sell rare goods, have a band of giants attack and scare off your cows! Pick your location carefully.
There is so much that can be done that would incentivise people to want to spent time in their homes and have other people visit. You would want to search out and try and find other people's homes and see what rare treasures you may be able to steal. It would add a whole new dimension and immersion to the game.