Let’s take one scenario at a time. Maybe you remember how ATI stated that Shader Model 3.0 was not necessary in its X800 and X850 series graphics cards, as it wasn’t being used by game developers at the time. This is the reason that ATI gave for failing to implement this feature in its product line.
Well, we now see that this statement is true, and there’s nothing wrong with leaving the feature out if you are talking about inexpensive hardware, which does not describe the high dollar X800 and X850 cards.
Now, I think NVIDIA knew that SM 3.0 wasn’t likely to be utilized as well, but went ahead and implemented the feature as a means of future-proofing their cards. After all, NVIDIA was working on its 6800 series for three years prior to the actual launch date, so they had to bring out something impressive after they had faltered with their 5xxx series. Otherwise, ATI would’ve continued its winning streak and NVIDIA would’ve fallen further down the revenue pipeline. More at CoolTechZone