Many seeds need a dormancy period before germinating, and frequently a husk or germination-inhibiting coating (Tomatoes) surrounds the seed as a delay mechanism: the coating/husk has to rot before the seed gets contact with soil and water. For many it's way of ensuring that seeds don't germinate at the start of Winter. For others there's a (sometimes long!) maturation process that happens within the seed (Macadamias) before they're ready to sprout. Other times the husk is there to protect the seed while it goes through the gut of some animal (often birds) so that it gets transported well away from the parent plant.
Nature is pretty clever, imho.