I suspect some of these examples also come down to making much hay of the lack of decimalization in Imperial units, combined with the way a name has been assign

I suspect some of these examples also come down to making much hay of the lack of decimalization in Imperial units, combined with the way a name has been assigned to just about every possible subdivision of each unit. 250mL isn't really any harder than a cup, nor is 500mL harder than a pint. And we could make them sound just as cuddly by assigning them special names. But I think a lot is lost in that, by way of usability. Here's a quiz: You're planning a party. How many pint servings of beer can you get out of a 15 gallon keg? Now let's do it in Metric. How many half-liter servings of beer can you get out of a 50 liter keg? I think most anyone will instantly recognize that in the latter case you just need to multiply 50 by 2 to get the answer. But most people will probably have to stop and think through a couple layers of unit conversion (four quarts in a gallon, two pints in a quart) before realizing that you can multiply 15*8 to get the first figure. Heck, I suspect that even among people who grew up with Imperial units a lot might get stuck without a hint.