It isn't that you can't have super-fantastic graphics and good gameplay. It is that you almost always have one or the other.
I think you can have both. How about Oblivion, Gears, God of War, Resident Evil 4, Metroid Prime, Half Life 2, Halo (at the time), Metal Gear Solid 2, Far Cry, Zelda TP (well..this can be disputed..), FEAR, Okami, Psychonauts and some others that I can't remember? Whether or not you like them, these were critically acclaimed games and many can agree they were known for having good graphics and gameplay.