In response to the first paragraph.
I agree that in most cases to be a good team you need a somewhat productive run game, but only to the point that you aren't one dimensional, and force defenses to play "honestly". I don't, however, believe you have to have a top tier, high priced back to accomplish that. In fact, if you look at either top contracts or yardage leaders, it seems there is little correlation with those things and team success. McCafferty might be the exception this season, but even with him, prior to being a 49er, his team's success was very limited. Tell me the last "elite" back that was instrumental in a Championship run.
Now on to your second paragraph.
If RBs want to collectively bargain a different cut of the pie, I have no issue with that, but......... they would have to do it within their own player's union. The cap is the cap. The pie is finite. If you want some sort of artificial redistribution of $, that's something for the players to do from within.
If the rest of the players want to kick back to a fund to redistribute to RBs, for example, I doubt owners would object. I bet other highly paid position players would, though. That should tell you something right there.
I'm sure that's not good enough for you, though. You are probably only interested if the team foots the entire bill, and no other positions suffer. That's not realistic, IMO.
The cap will soon be $250m per year. That's a lot of cash. If players aren't willing to spread the wealth amongst themselves, who's fault is that?