Over the next couple of months we plan to bring many of the performance improvements of these maps to other areas of Atlas as well as refining and adding to the Internet Maps collection.
As always, we hope you find these changes useful and we welcome your feedback.
Thanks for pointing that out. I have now extended the maps to respect the address family preference as elsewhere. So if you are logged in and your preferred address family is set in https://atlas.ripe.net/prefs, it should default to your choice as with other pages throughout Atlas.
While we completely understand and share your desire to encourage IPv6 as much as possible, the team also feels we need to balance that with the actual state of things related to measurements and probes. And that means we have decided to default to showing maps with the most information possible (which in this case means IPv4). We hope you understand our reasoning.