I see the value in that just fine (though the value is minimal given that you are probably always attempting to improve your chances of hitting, even against low defense foes, and in any case since this is an across the board issue you can't even use common tactics like targeting lower defenses because they're all equally boosted as monster level advances), but...
I just think this is silly. Because we're not talking about a one off fight with a high AC opponent who causes you to vary your tactics. We're talking about everything you encounter, forever, past a certain level as your attack bonus decays relative to your opponent's defenses.
Oh, and if you really believe that the intention was to make higher level fights more difficult across the board than lower level fights, congratulations! You've defended the monster defense progression by arguing that the challenge rating system is broken. And that expertise is broken.