I think what we're mostly talking about here, in regards to the difficulty slider - is that we'd like to see something where the harder difficulty levels not only make the game harder, but add in some of the "hard-core" game mechanics that some of us are wanting (Attributes that function closer to the original Fallout games, ammo and meds having weight, etc.)
The idea is that it could possibly be a win/win situation for everyone. For myself, setting the game on Very Hard still doesn't bring what some of what I'd like to see implemented into the game - it just makes enemies harder to kill. This isn't because I consider myself "1337" or "better" than any other gamers - it's just that for me, setting the difficulty higher doesn't make me enjoy the game any better (and that's not to say that I don't enjoy the game - quite the opposite, in fact.)
If the diff slider added in some of the more "hard-core" game elements that were lost in the translation from Fallout 2 to Fallout 3, then those who didn't like those mechanics could play at the normal difficulty (or even hard difficulty - reserving "very hard" for all the extra features and more complicated considerations) and those who did want those things in the game, could select the higher difficulty levels. Best of both worlds, the way I see it.