This is probably going to get me a lot of flak, but I honestly think that the concept of the Unsung Hero, as a badge, was a bad idea. I don't oppose its design; the ratio makes sense as it is in fact rewarding the unsung heroes of S[OFU]. The fact that it is not luck-based and that it is pretty much impossible for some high reputation users to get it is both acceptable and fitting for its purpose. I think that mechanically speaking the badge works very well at its job. What I am concerned is whether the decision to implement it at all was wise. Because seeing design motivation like this really makes me bothered by the implications:
This is not meant to be another badge amongst the 1400 badges Jon Skeet already has, its about giving these users that contribute in a less popular way an incentive to keep contributing.
When I see Unsung Hero and Tenacious, I don't see the encouragement of good activity like other badges are designed for. I see praise for users who missed out, users who work hard where others don't look, users who are unsung heroes. To me, this conflicts with the very nature of the site and the badges - when did we shift our focus onto the users instead of the content?
Is a user who participates more often in overlooked subjects more valuable than a user who gives the same kind of answers but also is extremely active in popular subjects? Is unseen content of relatively unspoken users truly of greater importance to the site than the unseen content of well known users? On the other side of this user focus, why has Jon Skeet become an actual reason to decide on the implementation of new features and rewards? Aren't we supposed to be weighing our decisions on the content of the users, not the users themselves? I always figured the general idea was that while Jon Skeet has a lot of praise for his popularity, beneath all of that was excellent content that was continually contributed.
What behavior does this badge encourage? Posting in low-visibility questions? Create a new version of the badge that lacks the ratio. Is it to encourage avoiding high profile subjects? If the specialist badges aren't enough then an antithesis to Generalist as devinb suggests is perfect. No matter how I read this badge, it is focused entirely on the concept of rewarding eccentric users instead of good behavior and content in the community. To me, this is little different than the people who give Jon Skeet upvotes just because of his reputation, which I always figured was discouraged.
I think it's great to highlight the people who tirelessly work without any reward. But the existence of these badges is basically stating "Participation in low-profile subjects is good, but only if you avoid high-profile subjects". Which is a horrible, horrible idea. Why can't we just encourage everyone to participate in low-profile subjects, especially the well-recognized experts who may know the answers?