The base units of the metric system are often not very ergonomic. Why is a meter so damn big? And why is a gram so damn small? I can barely detect a gram. And a meter is frickin huge, causing people to usually divide it into hundredths of a meter, which you can hardly picture in your mind unless you already know what it looks like, especially arbitrary counts of cm. Metric's only real advantage is that it shares the same radix as our counting system.
What we really need is a new system of units...