Well, to use your A100 goal, currently it takes 10B and 3S to reach Sergeant Major, which unlocks that challenge. Not including the other angels that come from this rank, there are 16 bronzes and 9 silvers that don't require winning the game. Even if we take out the HMP/UV ones for the silvers, there are still three very doable badges (four if you include Strongman Silver which REALLY isn't that bad). I don't think that this is too much to ask of the player.
Now if you're telling me that you've been playing the game for years (albeit casually) and you haven't won a game to this day, even on ITYTD, I'm not really sure what to say. Check out my badge guide if you're aiming for some specifics, or check out Thomas's guide for the basics on winning a typical game. As a rule of thumb, rapid-fire builds wreck most everything on easier difficulties, so I would stick with traits like SoB and EE if you're working on ITYTD/HNTR.
I don't think badges within the same tier (material?) should differ too much in terms of difficulty, though if we get to the point of having a lot of badges I can imagine switching things around and even rebalancing them in general. If you're really hankering for some other challenges you could always ask someone for their player.wad file just to mess around. Granted, most of the challenges that take longer to get are quite a bit harder than the more immediate ones. (For instance, there's a reason A100 is a Gold badge.)