I wonder if Location Accuracy has also the purpose of feeding new
locations of accesspoints to Google.
Yes,When you select the option to pin point you they use a wide variety of things.When it does do they also send data to better those services.Google initially started mapping wifi points using cars.
This summer it was revealed that Google Street View cars, besides
taking photos of your neighborhood, were also collecting the street
addresses, Wi-Fi service set identifier (SSID), and the unique Media
Access Control (MAC) identification information for computers, Wi-Fi
access points (AP)s, and routers
As for using your data to better their geo location services is also true.
Here is the official statement of such
Most mobile phones are equipped with GPS, which uses signals from
satellites to determine a device’s location – however, with Google
Location Services, additional information from nearby Wi-Fi, mobile
networks, and device sensors can be collected to determine your
device’s location. It does this by periodically collecting location
data from your device and using it in an anonymous way to improve
location accuracy.