Ankle mobility is essential to be able to squat properly. Without proper ankle mobility, the hips cannot drop low enough and the torso ends up translating forward.
If you are just squatting for normal, daily tasks to lift things up occasionally, over time you will start to develop pain. This pain could show up almost anywhere, depending what area is compensating most.
If you are a CrossFitter or trying to do Olympic Lifts, you will never get to your full potential if you cannot keep your torso upright in the bottom of a squat.
Try out this drill to improve your ankle mobility and as a result improve your squat.