Depends on what type of offense a team runs. In the Cowboys case it is foolish to underestimate the value of a good RB when the strength of our team is our o-line.
I think you could argue the opposite. With a great OL, you don't have to put a premium value on a RB.
Let's be honest, a lot of people thought McFadden would be a bum because frankly he was a bum in Oakland. And yet behind this OL, he basically averaged the same yards per carry Murray did the year before and finished with over a 1,000 yards and wasn't even the starter the entire year.
If Romo had been healthy all year, I think McFadden would have been more than good enough to be TB here.
It's an interesting debate. I tend to think you don't necessarily need a stud TB with this OL. You just need a competent one. So while I wouldn't waste the 4th pick on Elliott, I also wouldn't just ignore taking a TB say in the 3rd round if one is there that they like.