well, the other reason is to avoid exposing your home IP to the DNS servers of the world.
using e.g. 8.8.8.8 means Google and your ISP can log your dns queries and tie them to your IP, running your own recursor means every DNS server you touch knows you personally looked them up.
The threat of random DNS servers spread over the world knowing your queries is certainly orders of magnitude less than when using the Google or the ISP name servers.
For Google or for the ISP it is trivial to aggregate all your queries in order to have a complete history of your activity.
For many DNS servers distributed over the world and belonging to different organizations it is much more difficult to coordinate in order to monitor you.
In practice, your ISP is the main threat for monitoring your Internet activity, not by DNS, but by its routers, through which any packet sent or received by you must pass.
using e.g. 8.8.8.8 means Google and your ISP can log your dns queries and tie them to your IP, running your own recursor means every DNS server you touch knows you personally looked them up.
it's important to decide your threat model.