Running backs are valuable. They just aren't as popular as they once were now that the game has become more about QB's and passing. There are still popular RBs but it's like the bar is much higher now. A RB has to be elite right away (and it's expected every game) to get attention.
Frank Gore is amazing... he's still out there grinding and breaking records. He's now sitting at number 4 in the NFL's career rushing yards leaders, and the three names above him are Barry Sanders, Walter Payton, and Emmitt Smith. The guy deserves more attention and respect than he's getting right now. I'm sure he'll get it once he retires.
Speaking of RBs, I'd like to point out Adrian Peterson too. He's still pushing at the thirty year boundary now at 34 years old and is sitting at number 8 on that same career rushing yards list I mentioned above. And yet, as he continues to grind it out at his position, he no longer gets the same attention he once did as a younger RB.
It's a strange league.
RE: The return of the running back!