Like I said, you shouldn't believe everything you read out and about.
On the Mario 64 issue, I always knew it had less polygons from the moment I've seen it running. I use it as an example all the time too, as to how less polygons can look better.
Better than 1996 modeling, that is.
So here we go, this is the ripped Mario 64 model:
http://i.imgur.com/tCuFbT6.jpg
752 polygons. Whoa. That's more than child link from OoT (standing at 662 polygons, and notice how it looks so much better).
This was before polygon transformation/animation was common, and it was hardware intensive to do (Banjo Kazooie did so though, so banjo has 405 polygons) so instead developers opted to keep it to a minimum and sort it out by assembling models via joining "floating parts" as you can notice to be the case on Mario 64's case above.
So this is the first part of your refutal, next we have Mario 128, why? You'll see:
http://i.imgur.com/3eIrNFl.jpg
http://i.imgur.com/owPl9Qz.jpg
Video here.
How many polygons do you think those have? *drumroll*
Source:
http://cube.ign.com/articles/084/084030p1.html
They have less polygons than the original model for Mario 64 did!
See were I'm going?
Do you still think this:
http://i.imgur.com/Xp82wGy.jpg
Has more polygons than those GC models?
http://i.imgur.com/hPnBBnE.jpg
It's simply using the same more modern techniques, legs are paralelipiped blocks that animate on the joint for instance. It's 300/400 polygons at most, perhaps less. Also, there's no reliable DS model ripper (to my knowledge), but most DS 3D games won't ever think of using 700 polygons for a model, if anything because
DS hardware is capped to rendering 2048 polygons per frame!
Note: I found the Mario 64 model rip on my external HDD in a matter of minutes, but took this long because 3 people called me (and talked for a long time).
EDIT: As for Link from Spaceworld demo versus Link from Zelda TP... Link's model from TP has 6900 polygons which isn't a lot; The Spaceworld link seems way more detailed than that:
http://www.1amgeek.com/blog/wp-content/uploads/2011/06/FileZelda128.jpeg
We're talking as detailed as the model for a 128-bit high-end fighting game (with two character onscreen being the focus), it's just the texture un-skinned look or flat texturing going on that makes it appear more dated (ie: first generation modeling).
It's clearly way more detailed all around, including the face going by teeth/jaw outline detail alone... than this:
http://assets2.ignimgs.com/2005/05/...t-princess-20050517032706999-1123106_640w.jpg
Remember, less polygons doesn't necessarily mean worse, it just means less polygonal detail.