Having proper form during exercise is more than just about looking good. Sure, you want to impress that guy working out beside you, to show him that you know what you’re doing. But other than that, proper form during exercise is essential for two things: efficacy and safety.
Poor form especially in complex exercises like weightlifting can result in injury. You don’t want to have a broken back or limb, do you? Not only that, improper form also makes it more difficult for you to achieve your exercise goals.