Thicker line will often kink and crease easily. We also fit far less of it on our spools. Thicker line can be very useful when there is a lot of sharp cover and toothy fish. By and large, thicker lines will have better resistance to the abrasion caused by sharp structures such as rocks and reefs. It is also good for resisting sharp teeth. Thick line can be an issue, as fish easily see it. Often, the thickest lines we use are used only for leaders.