Anyone who's ever scraped lasagna off the bottom of a pan or had warm-from-the-oven cookies crumble to bits when trying to remove them from a baking sheet knows how essential quality nonstick pans are. With cakes, it's even more important to use this kind of bakeware.
You can always scoop tarnished lasagna into a bowl or toss cookie pieces onto a plate, but if the bottom part of your cake gets stuck to the pan, the whole dessert will be ruined. Sure, you could try salvaging some tasty cakey bits and spoon some icing over them, but you need the cake whole and unblemished if you plan on presenting it at a birthday party or sharing a few slices with friends. And really, isn't that what cakes are all about?