Most people don't care... Until they realise some random company knows their address, name, DOB, favourite food, browsing habits, friends and family, personality.........
This is all data, not furnitures. You owning it and storing it on your homeserver doesn't prevent a third party from knowing where you live and what you ate for breakfast.
There are various ways it could be nice. For example, only having one location to back up, if you want backups, rather than having to find the download-my-data link for every single service you use.
