The Wii's main purpose and intent was to provide a gameplay experience like no other. Graphics is not the concern of Nintendo with the Wii. The DVD - Blu-Ray argument is mainly the concern of the Xbox360 and PS3.
Even though gameplay is important to me, shitty graphics in favor of good gameplay doesn't justify spending 400-600 USD on a console. When one buys a 360 and PS3 one is paying for HD graphics on top of gameplay. However with the Wii, when one buys a Wii, one is paying for the gameplay.