In what way?!?! The consoles have local multiplay, better graphics, can play media like DVD, bluray etc and of course, can be put onto a 42"+ TV.
A handheld does none of that.
If a new fiesta comes out with new features, it will sell, just as if a new BMW 5 series comes out with new features. You are comparing a micra to an Aston Martin, and farmville to CoD. Stop it; it's absurd.
The primary way in which they compare is the type of electronic gaming they provide: that is far more relevant than anything you listed. And, in the Wii's case, it was the Wiimote and the rather revolutionary games Nintendo made as opposed to what you listed. I'd argue, indeed, that it is primarily software that drives sales (especially in Nintendo's case), which, is what both handhelds and consoles have, of course. So, to argue that which bolstered a handheld's sales (software, price point, etc) could not possibly do so for a home console is unwarrented, I would say.
That wasn't the original point though...I do agree that price point and content are essential, but then again that's a basic rule for any and all products. However I don't agree in people directly comparing sales figures of handhelds to consoles as the markets (read intended audience) are so vastly different it really is like comparing BMW to Kia, which is what other users were doing.
My point was that a comparison between the two is not necessarily invalid. I'm not saying that a comparison between the two is automatically correct, either. Indeed, what most people are doing when comparing the 3DS to the Wii U is merely positing the possibility, not inevitability, of the Wii U following suit. You can examine what caused the sales of the 3DS and see if they might apply to the Wii U (and, since the 3DS's price point and software content were adjusted, the essentials, all the more reason to at least hint at a connection to the Wii U's sale, should it do the same changing) and question if it will, but it should not be dismissed out of hand, I think.
Also, I do not think the difference between handhelds and homes are as vast as the BMW to KIA, or Farmville to COD.