I always thought it'd be cool if you would get an achievement from your Dashboard for certain things you do on Xbox in general. Like once you get over 10,000g that you'd get say... 50g? I don't know. Something like that. Or you have like over 50 friends on Xbox Live you also get 50g. Let me know what you think.
It doesn't really make sense to get gamer score for getting gamer score. Also, if there was an achievement for getting 50 friends, people would just spam friend request people.