I have a few ideas that I would like to share, idc so much about people's opinions as I do just getting them out there for someone who might be able to apply them can see them.

1: Players can offer vendor space to other guilds at their home. So if you have a big/active guild you might have a lot of bids on that location. Someone may want to be your guilds main supplier.
If you can't picture this yet (I hope you can picture period, some people can't and it's a real condition that you may want to google if you find that you can't form a mental image) try to imagine you're in Stormhaven on your way from the Wayshrine to the Undaunted Pledge area. Y'know how you see all of those guild vendors? Well, imagine that but at your guild house.
I think that we should be able to turn our property into small cities for ourselves/ guilds.

2: Which leads me into my next housing idea;
There should be NPC/Companions for everything like your stable and different types of vendors that you can have at your house. So now you don't need to go into a city to feed your mount.
I don't think it's called "feed" anymore, I'm just getting back to ESO after 5 years and back when it launched we gave our horses apples and stuff to increase stats.
There should be property specific NPC's/Vendors that the player can purchase and only use at their property, so these NPC's/Vendors don't need to cost so damn much...

3:Players should be able to open their property to all players, you could do this by making so when you click on a property door you're able to open a list of players who have made their home public. You could have your own vendor city, and players might come right there instead of going to whatever random guild vendor is closest.

4: Random player housing locations;
I can imagine that much like myself, you've found yourself running around the game and thought "This place is so cool! I would like to live here!"
I think there should be open housing in zones. Maybe not the zones that we're used to, maybe make new ones that aren't so populated with NPC's and quests but maybe just enemies/delves and such. This area would have large spots where the player could place house foundations to build on, or place a pre build house if the spot of land is big enough.
Also, it wouldn't feel right if we didn't have the option of purchasing land in general to landscape and build on, instead of simply placing a house/house foundation.
Players should also be able to do this in an area where it's not friendly, meaning that you can PvP there. For guilds that are PvP focused, imagine that.
Back when I played UO or UltimaOnline, I was in a PvP guild called BC and it was so awesome having the main guild house in Fell. We set them up specifically for PvPing with areas to fight from and hide in, to restock and everything. It was amazing.