The opportunity to interview for a position is almost always in your best interest in most any modern white-collar workplace. It's even more so in the NFL though.
Of course - look at how Tomlin "wow'd" the Rooneys when he interviewed for that position that was already 3/4 already given to Grimm or Whiz.
I just think that when an organization already has "their guy" picked out - think Jason Garret in Dallas in 2-3 years, it's insulting to bring in a minority candidate to interview simply for the sake of complying with a rule. Think of it like this - skin color should have no impact in who gets hired for any job, therefore it should have no impact in who gets interviewed for any job either...football or otherwise.