What are you talking about? Nintendo does have great third party support.
The only 1st party Nintendo games I own are F-Zero GX, The Legend of Zelda OoT/Master Quest, Metroid Prime, and Super Smash Bros: Melee.
My 3rd party games are Godzilla: DAMM, Resident Evil 0, Resident Evil, Resident Evil 2, Resident Evil 3, Sonic Adventure: DX. Soul Calibur 2, SSX Tricky, and Ultimate Muscle: Legends vs New Generations.
I plan on only getting two 1st party games this year coming and they are Pikmin 2 and Super Mario Kart: Double Dash!!
My List for 3rd party games are Wrestlemania XIX, Resident Evil: Code Veronica X, P.N.03, Star Wars: Rogue Squadren 3, SSX 3, Viewtiful Joe, Metal Gear Solid: The Twin Snakes, and The Simpsons: Hit and Run.