The prevalence of 3, 6, 12 multipliers is why Thomas Fowler's wooden calculator used balanced ternary.
Irregular multipliers for place value actually leads to fewer mistakes. The problem with the metric system is that all the multipliers are 10 or powers of 10. This is a featureless landscape leading to misplaced decimals. Once it become familiar, the rugged landscape of 2,3,5,12,20,60 etc multipliers prevents this type of error within the covered value ranges. (Once you start talking about millions and billions and trillions of pounds/miles/etc you have the same problem as the metric system.)