Depends how you look at it.
One school of thought for business is offer more of what people have been proven to like and are familiar with.
Sony are clearly taking the view that Nintendo have established the 'baseline' experience that people want and are going to offer something similar. This certain makes sense from certain business standards and isn't that odd. The risk is that, yes, they are late to the party, Nintendo are way ahead in the lead, and they just take a small amount of the pie.
Another says offer something different or a twist on the baseline - this is what MS are hoping to do. I'd say MS approach offers better chance for big success, but also has a bigger chance for failure as well, which is consistent with this approach.
If Sony are right, and most people now are expecting something similar to the Wii then Natal could fail badly for being too dfferent and too much of a jump and failing to 'bottle lighting' in the way Nintendo did with the Wii and if Sony are also right about people being up for more of the same but in HD or with their angle, then they'll sell okay.
If Sony are right and the above happens but the market size isn't as big as they hope, or isn't ready to consider seeking more of the same but with a jump to HD, then both Move and Natal would fail.
If MS are right then Move will probably fail for being late and simply 'more of the same' while Natal will see goof success and might even restablish the baseline away from the Wii motion controls.
So, for sure, MS are taking the riskier route but they might gain more, and for sure Sony are taking the low risk road but their success if it happens is likely to be more muted. Probably. Because you can never quite tell in advance.
Anyway, I think it's clear why Sony's approach is as valid as MS - it's about risk/reward and current position. MS is going to take a risk and try and really spread its wings, Sony I think wants to be more conservative and go for steady growth no doubt with an eye to regaining ground later vs MS feeling they need to be bold to get anywhere.
Try to be reasonable... its easier than you think...
