First, Temple, Cincy, SMU, Tulsa, Memphis, and UConn are not terrible teams. Quite the opposite and they have proven that for the most part year over year.
Second, the whole P5 thing is a self fulfilling prophecy. They start out with high RPI and SOS and then play each other which reinforces the same thing. They can choose which conference to "punish" by not scheduling them, making it impossible to move up. Further, if you play a P5 it is likely early in the season so teas with raw talent recruits generally can faire better against early season teams with project talent.
Third, this about money. Nothing more. The P5 needs to squeeze these schools into a second class citizen and drive up media market presence and control, which means more $$.
Finally, you don't take a 20 win National Champion, while admittedly spotty, and exclude them for the tourney. Let me put it to you this way, if Puke was a returning National Champion with 20 wins there would be no way in hell they would be dropped.