Probably a combination of size, shape and pricepoint. Graphic designers and focus groups have a lot to say about what products we get. If they like the angled look of a flip up flash or putting a hotshoe on top makes the camera look too square or bulky, off it comes. If something bumps the price by $25 and the consumer focus group says "I would pay $XXX.XX for this product" off it comes. Fortunately, there are more and more high quality ttl equipped slave strobes these days and I hear that the optical cords are improving as well. Many shops are now saying, "Why hard wire your strobe, our customers are doing great with optical cords on P & S cameras."