I dont agree with the notion that Gamecube was better then the Wii in terms of software.
It had almost no thirdparty support after 2003. Only Ubisoft, Activision and EA put their multiplats on it and those were normally not that great. In terms of japanese games there was definately much less going on then on the Wii. Sure Capcom put REmake, RE0, Viewtiful Joe and RE4 on the system and there was Tales of Symphonia, MGS TTS, FFCC and Baten Kaitos from Namco Bandai and Square Enix. But there wasnt much support beyond that.
The Wii had less multiplats but got some unique exclusive software from western publishers like Boomblox, Anno Create a New World, Rabbids Go Home, Redsteel 2 (wont count 1 because that was crap), da blob, a boy and his blob and dead space extraction or golden eye. Sure the number of multiplats is not as strong but if you think about it that was the same on the GC. Japanese Thirdparties however have greatly improved their support i believe. We had games like Muramasa, Little King Story, Trauma Team, Monster Hunter Tri, Silent Hill Shattered Memories, Rune Factory Frontier, Sakura Wars V, Fragile Dreams, Super Robot Wars Neo, 428, Chocobos Dungeon, Sonic Colors, Dragon Quest Monsters Battle Road Victory, No More Heroes 1 and 2, Dragon Quest Swords, Taiko no Tatsujin, Tales of Graces, Mad World, Tatsunoko vs Capcom, House of the Dead Overkill, Zack and Wiki, Okami, RE Chronicles series, the very best version of PES etc.
In terms of first party support there is no way to argue that the Wii lineup is way stronger then the GC lineup. GC had Zelda WW and TP, Mario Sunshine, Mario Kart DD, Pikmin 1 and 2, Luigis Mansion, Animal Crossing, Metroid Prime 1 and 2, Fzero, Starfox Adventure and Assault, Paper Mario 2, Eternal Darkness, Donkey Kong Jungle Beat and Konga, Mario Tennis, SSBM, Wave Race, Fire Emblem PR... and thats about it. Lots of games were, while being good, dissapointments overall (Wind Waker had a great Look but was shallow in terms of gameplay, Sunshine had a neat Idea and features some of the most hardcore platforming levels but had a lot of flaws, Mario Kart DD had a nice Idea with the character swap system but it was low on content, Starfox... eh)
The Wii had Mario Galaxy 1 and 2, ZeldaTP (and soon Skywardsword), Xenoblade, The Last Story, Fire Emblem RD, Excitebots, Excitetruck, Punchout, Wii Sports and Resort, Wii Fit, Wii Music, Wii Party, Kirby Epic Yarn, New Super Mario Bros Wii, Donkey Kong Country returns, Smash Bros Brawl, Metroid Prime3 and Triology as well as Other M, Animal Crossing City Folks, Mario Kart Wii, Super Paper Mario, Wario Land Shake it, Sin and Punishment 2 and Endless Ocean. The big hitters delivered really well (Zelda TP is the best 3D zelda in terms of dungeon design, Mario Galaxy is considered the best of the series, NSMBWii is the best 2D Mario -and i played SMB 1,2,3 and SMWorld as well as Yoshis island- with an excellent multi player option, Brawl had the most content a game ever could have etc) And a lot of new stuff rolled in (Wii Sports, Wii Fit, Wii Music, Endless Ocean, Xenoblade, The Last Story, Punchout, Excitebots and Truck)
The Wii lineup is way more varied then the gamecube one in terms of quality and quantity.