Umm... No.
It's not like there's some magic formula where CP = power.
CP is just a representation of the pokemon's power.
Surely, most people realize this when they choose a lower CP pokemon that has better moves. For example, choosing Meteor Mash Metagross over Dialga eventually.
The reason attack is more valuable than defence and HP in the CP formula is because it matters more. Attack is the ONLY stat relating to how much damage you deal. Defence and Stamina both contribute to how long you survive. Thus, attack is more important to overall power.
Further, at least how the game is played for now, DPS is king. Lowering the CP of stronger attackers will just make it more annoying for us to scroll through our legions of tanks to get to the pokemon we want to use in raids to get the most damage balls...