I'll preface this by saying that this isn't an argument in favor of the imperial system, nor is it an argument intending to detract from the usefulness of the metric system. But I have wondered if there is some merit to having a simple, colloquial, "human friendly" system of measurement — something that's shown to be the best system for people to grok, and is the most convenient to use in day-to-day life. If you need precision, and well defined standards, then certainly use the metric system, but is the metric system easy for people to grok? Say you ask someone to estimate a length. Would they be more likely to accurately estimate the length using the metric system, the imperial system, or some other system? Likewise for telling someone a length and asking them to physically reproduce it. Would they be more likely to do so with the metric system, the imperial system, or some other? It's an interesting problem, imo, and it doesn't seem to get much attention.
It could very well be that people can, indeed, grok measurements the best when using the metric system, but I currently am unaware of any research that has been done to show that. If anyone is aware of any research that has looked into this, then please let me know! I'd be very interested to read it.