Advantages: All units in the Metric system are scalable by ten. For example, 1000 g = 1kg. Disadvantages: It would cost a lot to change to metrics. Also, many sports are linked to customary measurements (track, football, etc.)
People are resistant to change.Now that most countries have been using the metric system in science and engineering for several years there are likely to be few practical problems. Some Luddites...