However, as you noted, passing the Earth at some 60,000 miles is not like we are going to notice the inaccuracies in conversion between metric and english units, much less any normal earthling noting that "gee, was that an asteroid that just passed the Earth?" Within the past coupe years, there was an asteroid that passed within the orbit of geosynchronous satellites which is 22,236 miles or 35,786 km for the conversionally challenged.
And as to missing them, there are probably many more that science misses, too. Its just not a high enough budget priority.
Agreed. And Americans do not use meters/km/kg/cm etc. The US military uses metric for distances like meters and km by necessity; but your average American does not give 2 sh*ts about the metric system.