Yes, there is that problem in getting the starch out of the grain kernel. However, you can't boil the base malt before mashing since that would denature the enzymes needed for starch conversion. Exposing more of the kernel surface area via finer milling is one way to improve extraction. An additional consideration is that the mashing process should extract more of the starch if the mashing temperature is eventually brought to a fairly high temp such as 168F as part of a mash out step.
Jeff, while I agree that pH can play a part in tannin extraction, I still believe that its the high wort gravity and the osmotic stress it places on the remaining husk and kernel matter that helps limit tannin extraction during decoction. We can keep pH low throughout sparging, but if you let the final wort gravity get too low, you will extract tannins from the bed.