I like having more choices for units. Sometimes the "correct" unit is extremely inconvient to deal with, either because the unit sizes are oddly out of proportion with the things being measured, or the things being measured have odd ratios with the units. Sometimes even making your own unit system or going with pure ratio relationships between objects is the most useful and effective way to measure things. And I feel that people who only ever use a single system of measurement often fail to see it and put themselves at a large disadvantage.

To me using only a single system of measurement is the same as only ever using a single number base. Yeah it helps to have a standard number base everyone can use like base 10, but that doesn't mean we should try to eliminate other number bases from our vocabulary or understanding because they obviously have situational advantages.

Also from my personal bias I much prefer fractional measurements and people go apeshit if you use fractional metric units but don't blink an eye at fractional imperial or other 'non-standard' measurements.