Ryan Seacrest -- I'm No Dummy ... Fighting's Great for Ratings!

There's a reason Ryan Seacrest is so rich ... he KNOWS conflict makes shows successful -- claiming yesterday's Nicki Minaj-Mariah Carey blowout is a good thing ... for "American Idol" ratings.

Seacrest just took to his radio show, addressing the TMZ video in which Nicki goes off on Mariah during an audition Tuesday. Ryan said, "We want that!"

"We want them to be on this panel together. This is a good team, a great team, to go out and look for the next American Idol."

Seacrest said, "[There's] nothing wrong with disagreeing ... That's gonna happen, and it's okay."

He added, "These are all very different individuals with different perspectives and different opinions that provide for interesting conversation and dialogue and feedback for the contestants."