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BOM is certainly part of the costs of a product, but you are all forgetting the costs of R&D that need to be taken into account as well. Accelerometers were nothing new back then, they just became cheap enough to be implemented in the controller. Also note that IR camera introduced in the Wii remote... two new inputs that differentiates it from the Gamecube.
And that's only taking into account the technology side of it, afterwards you have the implementation in the software. Developing something like Wii Sports, how many brainstorming ideas, demos, and test they must have done to nail the gameplay with this new scheme control. The same goes with the IR controls and how it influenced the design of the OS.
With the Switch 2 we now have the mouse pointer sensor, that should be super cheap, but the implementation in the joycon, that costs a bit.
