I suppose they could know this to be true, but their actions thus far have implied that this is not the method by which they are approaching the development of their new interfaces.  Nintendo was showing off Wii Sports from day one, and the Wii was designed specifically to facilitate experiences like Wii Sports.  The hardware was designed with that game in mind.  They had a vision of what type of software they wanted to achieve from the getgo.

In the case of  of Move, it seems as if Sony simply wanted to capitalize and improve on this now proven hardware design, allowing developers to make use of all that it offers on their platform in addition to the Wii.  As a result, we've yet to see any form of a killer app for Move, instead mostly seeing Move controls implemented into previously existing titles, like Killzone and Socom.  We've seen some amazing tech demoes for the device come out of Sony's R&D segments, but they've been nothing more than tech demoes thus far, like that minority report video or that new method for controlling RTS games.

Of course, this strategy isn't necessarily a bad one to take.  You're working with proven technology, so there's little risk involved, and Sony has shown in the past that iterative technology can be quite succesful (SNES > PS1).  However, the overall potential for success is far less than when tackling a new market segment, ala the Wii and Wii Sports (and later  Mario Kart, Wii Fit - for which they designed yet more hardware to achieve what they wanted in software, and all the other > 10 million sellers that rejuvinated the Wii's sales when things started to slow down).

And given the Wii's downturn in sales as of late, it's unlikely Sony will be able to rejuvinate interest in this market in a way that Nintendo seemingly cannot.  Wii Party has the potential to pick the Wii back up, but if it does, that's suddenly one more genre where the Wii will have beaten Move/Kinect soundly to the punch.

In the case of Kinect, it seems Microsoft simply looked at what Nintendo was doing and tried to think of a way to make even more accessible hardware.   Nintendo went with a remote-like device to limit the number of confusing buttons players would have to handle, while Microsoft got rid of the need for buttons entirely.  However, we have yet to see any sort of grand vision they had in mind when building this hardware aside from, "Look!  No buttons!" 

They showed numerous tech demos at E309, many of which have been deemed unfeasible with Kinect in its current form, implying that they were focusing more on the hardware itself rather than prioritizing that the hardware will be able to enable what software ideas they had in mind.  And even these tech demos merely showed off gameplay ideas rather than full products.  It's like they said "Here's some things our hardware might be able to do.  Cool, ain't it?  Let's hope somebody decides to use this in a game!"

Now we've actually seen the builk of retail software in the works for the device, and it's nothing but clones of Nintendo's best casual and bridge titles, like Wii Sports, Wii Sports Resort, Wii Fit, Mario Kart, and Nintendogs.  If they had been focusing on software from the getgo, they'd have something more imaginitive in mind, I'm sure.

Hell, the closest title Kinect has to a killer app is Dance Central, a game that isn't even made by Microsoft.

And sorry for not replying earlier.  Been rather busy lately!  If I see you on, I'll be sure to say hey.