I recall that GM was in some kind of lost phase about when all of the cars were getting those GM badges on the sides, there was less emphasis on the divisions and model names and more on the Generic Motors branding.

 

I think the idea with the silver was to keep it all in the "driver zone", so making a silver bezel for the passenger's vent way over there would just make it visually stick out. As it is, it looks good to me; handsome, in fact.
Overall, I like it more than the 6th-gen's dashboard.

The only little thing I wish they wouldn't have done (for both 6th & 7th) involves all those separate adjuster slots by each vent -- cluttering, and not even necessary.

 

So, the silver is on the passenger door because...?

 

You mean the armrest bezels around the power window switches?
... because, like the upper driver's panel, it visually complements (accents) a complete form. By comparison, the MC's passenger-side vent is just a square sitting there by itself; no styling lines connecting it to a corresponding form on the driver's side, or anything on the passenger's door.



Hope that helps; if not, here's an Impala dash with lots of silver, door to door:

 

I guess this shows again the original 'answer' is that GM styles 'sportier' cars a bit differently, ie they turn the center console in and color the area differently. They did it for 2004-2008 Grand Prix. Then again they did it for the Aurora too now that I think about it...

 

I would guess its inspired from the 4th gen. The 4th gen dash is "spearated", as in the gauge cluster is boxed in and the rest of the dash is another piece.

 

Oh, and something I just noticed today, looking at an '04 (and it's evident here, too, you just have to squint):

There's a vertical line demarcating the vent from the rest of the dash in the '06-'07 that isn't there in the earlier version. So no, it ISN'T unchanged, and I have to ask again: why not do that last little bit of change?

 

And I really miss not having those six gauges. Peeked inside a current Regal today, and that instrument panel is even worse....

 

Looks better than faux wood...

 

Could always get you're own wood, stain it and insert. Probably more work than it's worth and many probably don't have all the tools.

2006-2013 (14? some look like that) Impala's never did it for me anyway. The exterior is rather boring. Interior does look more refined.