My 11 year old put it very succinctly as she watched the finale. "This isn't American Idol, its American Teen Idol".
That is the show's viewer demographic and they play to it. Randy's simplistic, moronic feedback (In It to win it"). Jennifer's cloying personality, her um, music video's ....and Steven's placating "I loved it" blurbs are not just teen friendly, they are intended to appeal to that crowd. Haley was fun to watch because she improved so dramatically, but listening to the three stooges (judges) was excruciating this year so I opted out once she was shown the door.
The show was already headed to "Teen Idol" status before Simon left. After last year's down ratings they finished the transformation. They dumbed down the feedback, lowered the age of entry and got what they wanted... Young viewers, young winners and content that makes it difficult to watch for 20 and ups.