v20 Motion X currently has the original map sets from way back in v16. When I emailed them regarding the change it has to do with licensing. It was suggested the maps will be back in a future upgrade. These guys upgrade the app a lot.
MotionX didn't have topo maps before, it had, and continues to use the Open Cycle maps. What was lost was Bing and Bing cacheable maps. As you pointed out Google maps is missing as well but Google maps weren't cacheable so the usefulness was limited. More on Google Maps... Motion X uses Apples Map Kit functionality so when iOS 6 moved from Google based to Apple based maps the change happened in MotionX. If you have an iOS 5 device you are still getting Google maps.
I posted in a separate thread that current users may want to wait and NOT upgrade to v20 of the app.