Personally, I find the prefixes helpful when memorizing approximate values, eg for back-of-the-envelope estimates (proton mass is 1GeV, electron mass is .5MeV, room temperature is 25meV, h_bar c is 197 MeV fm, ...)
A valid defense of the metric prefixes (I mean, I still think they're on the balance a mistake, but you do have a point), but ironically, electron-volts are not an SI unit.
