First, these shots are not comparable. You have to show us 2 identical scenes on the two said consoles. Not 2 different scenes.
Second: To have more horsepower does not mean to have better graphics. GC was far superiour thatn PS2 and XBox, but with almost no excluxive engines on GC, taking advantage of the machine, there were no miracles. Period. Even RE4 looked good, but not excellent. Watch the port on PS2 - this one was almost(?) as good as GC-port.
But it is there: You can give us more on Wii. PS2 has so small a texture-RAM, that Wii can easily have more and sharper textures. You can advance polygon-count on Wii and so on. But you have to write an engine for Wii/GC, since all the benefits of this hardware were swallowed by engines good for PS2, Xbox and CG alike. There where almost no tweaks done for GC. Check PS2. This rubbish piece of hardware (how old is PS2? You see?) has excellently been wizarded and tweaked. Just look at Final Fantasy 12! So I demand that on Wii also! You hear me, developers? Give me Twilight Princess x3. It is possible (since TP is a GC-title).