I don't think this as contentious a notion as you seem to infer.
The madden dev's can't program the CPU to exploit problems within the framework of the game that HUM players recognize quickly and use consistently.
A human player can easily disrupt a CPU 'stretch of success' by utilizing something unrealistic within football but successful within the framework of the videogame (certains blitzes, tosses on the goaline, slants/drags and other plays that have a higher level of success than they would in a 'real' game regardless of ratings, personnel etc.). This isn't a condemnation per se- in a real NFL game, they 'exploit' anything and everything as well. Your opponent AI is static and unadjustable once the game is shipped however.
People would be out for blood if the CPU recognized 'success' (again, nano's, certain routes/plays) within the game and exploited it without any HUM recourse within the framework of the game.. even though t
hats what HUM players do to the CPU and each other.
The HUM can't 'outcall' an unrealistic play by the CPU, like a crazy interception, just as the CPU can't 'outcall' the use of 'money plays' or tendencies used to a varying degree by the HUM player.
The solution would be to balance out the game and iron out kinks in the game interaction, but for now the alternative is to arbitrarily boost ratings (or however the difficulty system works) to increase difficulty- its the only way to ensure the CPU can consistently be competitive with the makeup of the game.
If you had only the AI playcalling adjust to increase difficulty, the possibility exists that the highest difficulty setting won't be 'difficult enough' for players that utilize ******** nano's and whatever (hey, their game, whatever) that operate independent of proper playcalling.
Think about the constituent base for madden.. as much as I would like to say its sim players, you need it to function for everyone, including the guy who runs the wildcat every play, etc.