ok, there may be little need, but for the price, its just not there right now i dont think.
i bought my current machine for a few key reasons. one was the larger screen for sure. the other two really being the gfx card, and the simple fact the machine came with 1gbx1 of 667, saving me more money down the road.
there will always be a market for something new and different, i just dont think its really worth it to apple. theyve always had a slim-pickens product line approach, and i think it works for them. their products are easier to tell apart because of it.
would i have looked at a 15" NON PRO? sure, but considering the current macbooks start at around 1200-1300, whats the 15 gonna cost, 1500? thats pro territory to me.
just my opinion. not intended to hurt anyone's hopes

edit: stupid edit button! another thing u have to look at is how apple sells their computers. theyre not a dell. meaning dell builds one machine of each size, and allows the user full customization (if they want a low end c2d or high end, int gfx vs ded).
apple just doesnt do this. they offer three machines. the 13" which is a great buy, with decent cpu's. and then there is the high end 15/17s, which comes packed! they want to distinguish their lineup differently than their competition. and i think thats great marketing.