I think that if you extended automatic invitations to every Power 5 conference champ (with a sixth berth in a six-team playoff to the highest-ranked Group of 5 champ), it could even out recruiting a bit, especially in the South.
If you're Nebraska, Iowa State or Colorado, for example, you might have a better shot at a top-tier Southern player by saying, "Listen, other than Alabama and Clemson, you have no shot at being in the playoffs. Come here, and give us a shot at the Big Ten (Pac-12, Big XII) title, and we'll get you into the playoffs."
Of course, all those Florida players might get one hint of a Midwestern winter and head back home to play for FAU or FIU, but that would be a boon for Group of 5 programs that already play at a high level (Boise, Cincinnati, UCF, Houston, etc.) who would have a shot at a playoff berth as well.
As it stands, you can pretty much pencil in only the SEC champ and ACC champ, with a second SEC team or Notre Dame filling the third spot, leaving the Big Ten, the Big XII and the Pac-12 out of the running unless they run the table and go 13-0 (or 6-0 in OSU's case this year). That's a tough hill to climb, one that an SEC team or Clemson generally doesn't have to scale.
And to say that one team is obviously better than a team from another conference is often based only on win-loss records, often in the same conference, or from games played between conferences in September. And as we know, in a normal season, most teams change over time.
As for Iowa, they'd have to up their game and start shooting for championships instead of printing t-shirts for second- and third-place finishes, their current apex and measuring stick for excellence.