Logical does not mean practical. Cut that board to 3,130.55 mm, or 313.055 cm, or 31.3055 decimeters. We could use it in foot/inch style: 31 decimeters, 3 centimeters, .55 mm. Or, you know, "ten foot three and a quarter" or 123 1/4 inches. Which one is easier?
Metric works alright for measuring...