I look at the situation this way.
We have the most productive offense in the entire league. Is it because we have a good rushing attack? No. It's mainly because of Drew Brees and a nice mix of skill position players. Why draft a guy at number 14 when we don't even have a need for him. Bush and Thomas have the skills to get the job done on that side of the ball.
Defenses in the NFL these days are desigend to do two things.
A. Stop the run
B. Pressure the QB
The way to counter defenses is by having a QB who makes quick decisions, building an offensive line that can block, and having skill position players on the field who can catch and beat their man when in one on one situations.
The days of having a dominant running game are over in the NFL as most quality teams in the league can stop the run if they know its coming. You have got to be able to throw the ball and make big plays. We have that ability already. No need to invest a first round pick in a workhorse RB when our offense is designed to spread the ball around. We need playmakers on D. We need passrushers and guys in the secondary who can intercept passes.