Citrus fruit, papery skins and often piths included, taste wonderful cooked, baked, sauteed, whatever. The seeds on the other hand, release a very bitter taste when cooked. If the seeds are not removed prior to cooking, an otherwise perfect dish/dessert will be doomed. So you’ve got to remove all the seeds.

Of course, most fruits are cooked without their seeds for similar reasons. (Peach stone pie? Pass.) The problem arises with citrus simply because it is customary to peel and section citrus fruits without a knife. Which makes it very easy to forget about removing seeds. Voila! Disaster strikes once again… :)