Metric is better for tool measurements. Hands down.

If the metric "9" socket is too big, what size do you grab next?

If the imperial "1/2" socket is too big, what size do you grab next? A 7/16? A 15/32? A 31/64? Who fucking knows, typically the answer is 'whatever is next to the open hole in my toolbox cutouts, assuming I have them'.

One is much easier to answer than the other, which requires nothing more than rote memorization of 'standard' fractional notation and mental division.

Metric becoming standard on vehicles came with an additional advantage, they basically decided to make the 10mm the socket that will work on 95% of the bolts in the entire car. Nice round number.

Metric is better for tool measurements. Hands down.

If the metric "9" socket is too big, what size do you grab next?

If the imperial "1/2" socket is too big, what size do you grab next? A 7/16? A 15/32? A 31/64? Who fucking knows, typically the answer is 'whatever is next to the open hole in my toolbox cutouts, assuming I have them'.

One is much easier to answer than the other, which requires nothing more than rote memorization of 'standard' fractional notation and mental division.

Grabbing the "8" will always be faster and easier. If they want to use metric on every single measurement of my car, more power to them.