Except thats not true at all. Wiis are so much easier to wire up. So many less wires without the modchip, memory card, and other stuff. Just wire up your power, U10, USB, AV, and controller and you are good to go. Thats like 11 wires to the board total, including the U10 wire. All the other stuff is optional to add features like RTC, Wii remotes, and wifi. A wiikey alone is like double the number of wires, and a memory card is 6 wires plus power rails.
As for the extinct modchip being the only reason people don't make gamecube's anymore, here are a few more off the top of my head:
Runs all GC games natively
Plays other games and homebrew
Easier to trim and wire up
Biggest wii trim is smaller than smallest gc trim
Less likely to fail for no reason
Less expensive
Uses substantially less power (longer battery life)
Creates substantially less heat
Doesn't need an extinct modchip
Doesn't need memory card
480p without $300 cable
Supports media larger than 32gb