Lets face it, whats the difference?
Inches are bigger than mm. Decimal inches and decimal mm are handled in
exactly the same way. The biggest arguement is fractions. Metric rarely uses
them.
Other than that it's all down to what we are familiar with. People can
imagine a man who is 6 ft tall because they are used to that.
We (UK) used to be imperial. we even had strange money called shillings and
pence. That was really cruel but some folks missed it when we went metric.
Could you Americans manage with 20 bigthings to the dollar and 12
littlethings per bigthing? Your money is metric, so are the number of your
fingers and the design of your numbers. All we have to do is get used to the
units. The base 10 system works far better.

John