Do you really think changing to metric means we'll stop using d/m/y dates?
Of course not. I'm just demonstrating the hypocrisy of the argument. A lot of people in this discussion aren't really arguing that we should all use SI/metric units across the board, they're just saying they want everyone else to use them when they do.
And for liquids, I've been buying 2L bottles for decades now, and you don't order "0.28L," you order (in Germany/Åustria) "kleine" (0.3L) or "grosse" (0.5L).
So do we, when we buy soft drinks. But in my country, we order beer as a half-pint or a pint, and everyone knows what they're getting. Are you suggesting not only that we should change our units to fit your preference but also that every drinking establishment in the country should buy a complete new set of glassware that will hold different volumes that are more convenient in the new units as well and presumably that everyone's prices should slightly change to match?