It should be easy for Garmin to add more badges but we'll likely to voice our thoughts to get them to action it. The people behind the Garmin Twitter account said to use the Have An Idea? page to suggest ideas for more badges. If enough people ask for it, perhaps they'll make the time to add new badges. There isn't much point in "gamification" per se if there aren't always more badges to strive for.
I suggested the following for new badges:
- badges for 5MM,10MM, 15MM, etc, steps
- badges for 1st races of varying distances (10KM, 10 mile, half/full marathon, etc)
- support for receiving a badge more than once where it makes sense (eg: the double, triple goal badges)
- fun distance badges (eg. walking/running the equivalent distance around the world)
- weight based badges (achieving your goal, maintaining your goal for XX weeks, etc)