The attack surface console makers are typically concerned about is one which the users have control over - jailbreaking the restrictive OS to customize the soft

The attack surface console makers are typically concerned about is one which the users have control over - jailbreaking the restrictive OS to customize the software, run custom software, and potentially run pirated games. So, if there were a method to do so through the disc drive, users would indeed go through the relatively minor effort of temporarily unplugging the console to force the disc to be used. Thus, what they're doing wouldn't reduce the attack surface at all.