I’m going to address here the argument that using inches, feet, cups etc. is somehow more natural or more compatible with how we think. I think that is not true and it is just a misunderstanding of how we estimate length, weight and volume.
While this is based only on my observations, I think it is safe to assume that other people do it the same way. When a person is asked to estimate the height of a tree just by looking at it, they use something they know the height of, like their own body or a car, mentally project it next to the tree and then give their estimate in multiplies of their imaginary reference. This process is the same no matter what measurement system is the person familiar with. The only difference is, that they will say “about 18 feet” instead of “about 6 meters”.
People just use objects they are familiar with to get a feel for how big is one foot or how heavy is one pound. If they use the metric system instead, they have a feel for how big is one meter and how heavy is one kilogram. That is it, both systems work the same during our every day measurement guessing.
Really, there is only one meaningful difference between the imperial and the metric system. In the metric system, you have to remember less names and numbers.
For length, imperial has inches, feet, yards and miles, while metric has centimeters, decimeters, meters and kilometers. For weight, imperial has ounces, pounds and tons, while metric has grams, kilograms and megagrams (even though people keep calling it tonnes). The prefix is the same, so every additional property brings only one new word to remember. In the imperial system, every property has completely different names. They also have completely different conversion rates, while in the metric system it is all just a multiply of ten.
Therefore, the metric system is better. Not by much, but it is. If you want to switch to it, the only thing needed, is to replace the numbers you remember for your daily references. Your foot? About third of a meter. Your old laptop? Three kilograms. Your beer? It better be a half liter. So, America, metric system when?