Claiming that die-size differences is desperate pretty much discounts your opinion ...
You can get a rough approximation of how powerful a processor is by looking at how many transistors a processor has and multiplying that by the clockspeed it runs at; this is by no means perfect but is far more accurate than simply looking at the clockspeed alone. The number of transistors a processor has determines its die-size for a particular manufacturing process. Being that the Gamecube used a 180nm process and the Wii uses a 90nm process, if the Wii used the same number of transistors it would have 1/4 of a die-size; the Hollywood and Broadway processors die size is 1/2 of the die-size of the Gekko and Flipper which implies that they have twice as many transistors.
Being that the Gamecube was already noticeably more powerful than the PS2, and the Wii potentially has twice as many transistors running at a higher clock speed with much more memory than the Gamecube it is fair to say that the Wii is far more powerful than the PS2. Now, let's look at the PS2 vs. the Wii ...
God of War 2 is considered by many to be the best looking PS2 game:




Compare the texturing, lighting, material effects, particle effects, and the quantity of geometry and it becomes clear that the Wii is far beyond the PS2.
Stop looking at this from one side, claiming that the Wii isn't as powerful as the PS3/XBox 360 and therefore isn't closer to the middle than it is to the PS2 ...