This, I can agree with.

Imperial system seems more practical to you only because you're used to it.

Celsius is practical because 0 degrees is when water freezes and 100 is when water evaporates – and water is something you encounter every day. We say "above zero" or "below zero" and easily understand what weather it is out there, or whether a product should be stored in the fridge or in the freezer, etc.
In Fahrenheit, meanwhile, 0 is… um, when some arbitrary substance freezes? And 100 is the normal body temperature. Yeah, very practical in everyday use – after all, I measure my body temperature ten times a day!
Nobody ever says "13.333333 deg. C" in everyday life – whatever for?! "13 deg. C" is sufficient enough. Fractions only matter when you measure, say, body temperature – but even then, everyone knows that 36.6 C is the norm. One decimal point is not so hard to grasp.

Of course a kilometer is not useful for measuring land, since a kilometer is a unit of length, not area. A square kilometer, on the other hand, can measure land – although an are (100 square meters) and a hectare (100 ares, or 10000 square meters, or 1/100 square kilometers) are more useful. See how beautifully they correspond with standard metric units? Can acres do that with other imperial units? No, because an acre is 43560 square feet, or 1/640 of a square mile. How utterly convenient!
A kilometer is not in any way less useful for describing walking distances than a mile.