Wii and the HD consoles both break immersion, but at different points of interaction.
Both consoles are stuck with the limitations of the TV screen. No matter how high res or photorealistic the HD consoles' graphics get, they're still stuck showing an image on a 2D screen. Though head-tracking could make some powerful and immersive 3D illusions in the near future, right now PS360 and Wii both stuck with a 2D image, even if one of those images is more detailed than the other.
The big immersive advantage of the HD consoles right now is 3D surround sound. This requires the right audio setup, but it's clearly more immersive when sounds that come from behind the camera in the game are emitted behind the player. Two-channel stereo can't compete.
Wii has an obvious advantage in immersive controls. When I aim the Wiimote differently in MP3, Samus similarly changes her aim in the fantasy world. When I point and squeeze the trigger, she points and squeezes the trigger. Thumbsticks and button presses add a level of abstraction that distance the player from their in-game avatar, and obviously, the Wii is still somewhat bound by these limitations for most games.
I hate semantics arguements, but I disagree with your usage of the word immersion, swyggi. When you talk about how players can get more immersed in the game if their arms don't get tired when they swing a sword around, well, to me that's abstraction, not immersion. It's a disconnect with the game world, because swinging a sword around is in fact tiring.
I think a better word might be escapism. Letting your in-game avatar do all the hard work while you comfortably tap buttons on your couch isn't immersive, but it does allow you to escape the physical limitations of your own body to a greater degree.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.
