If I extend my right arm to the side, the distance between my left shoulder and the tip of my right-hand fingers is a metre, give or take a couple of centimetres. This is a quickie way of measuring fabric, for instance, and a handy reminder when mentally visualising smaller measures.

Imperial measures may be more "human" (though basing your system or the size of someone's foot, leg span or walking speed, be they who they may, seems a bit dodgy to me ), but they are not as easy to work with as metric. As Hyla says, the correspondence between weight and linear measures is incredibly helpful.