12 and 60 divide nicely. A quarter of a 12-hour clock is 3 hours, but in decimal time it'd be 2.5 hours. A third is 4 hours in base 12, but some gross 3.33 repeating in decimal.
Metric isn't better because it uses 10, it's better because it uses the same base for everything. A measurement system (and number system) that uses 12 for everything would be better than both imperial and metric.