it's more practical, even if you don't choose to understand why. 12 might seem like a strange number of inches for a foot, but it allows for even division into two, three, four, or six parts. Inches themselves are split into halves, quarters, eighths, sixteenths, etc. which makes perfect sense when you're constantly doubling and splitting things like you are in construction.
Believe it or not, it is practical utility that keeps the US system of measurements going, not boorish stubbornness or the triumph of tradition over reason.
I think it's familiarity.
Builders around here have no problem at all and they would have adopted the more practical system otherwise. The UK especially wouldn't have gone backwards if it was a backwards move.
You can divide a meter in two three four or six parts just as well.
It's 50 cm, 33.3 cm (if you need a precision of more than one mm we're outside the scope of manual work and construction as not even a pencil is thinner than that, let alone an hand-held power tool), 25 cm, 16.6 cm.
Oh and here's the kicker: if you take a calculator, write 1 into it, and divide it by 6, you get the number you're looking for! No need to account for units of measure and convert fractional feet to inches!
Also familiarity induces people to do the easy fractions and get nice numbers, and the standard panel sizes and stuff also reflect the measurement units.
16.6 cm is weird, so people and industry don't use it at all. You can't buy stuff that is 16.6 cm long.
So it's all about familiarity.
You're used to dividing stuff in 6 parts and get nice numbers, people in the rest of the world maybe just divide it in 10 parts.
Reverse argument: 10 cm is an extremely common length, dividing by 10 is very common because we all use base 10 numbers, yet in imperial units it's 3.937 inches. How unpractical is that?
If the US had to switch today, it would be unpractical, until the common sizes that everyone in construction and bricolage is familiar with start to change.
NATO bullet caliber sizes are written the ugly way and that's not a problem for anybody.
When it comes to high precision e.g. in industrial production, you have to state uncertainities and all that stuff anyway so nice numbers do not help in any way (you always have uncertainity), so it's more practical to just use units that follow the base 10 system.
If you already have a system for temperature that everyone knows, why use something different?
that's why there's no effort towards metrication. The US is huge and self-contained in many aspects so they don't need to sustain huge costs to maintain a different system. Importers of construction materials can adapt sizes without too many problems since it's a huge market. Where this is not practical (science), the standard units are used in the US too.
Now try to do the same in Europe, and exporting for a company that produces small amounts of components of various sizes becomes a mess since they have to do everything in multiple standards.
The English with their left-hand driving non-sense are scary enough already. You can look into a car and see the driver reading a book with no wheel in front of him. Then you see the yellow plates and have an a-ha moment.