The argument about the relative merits of Imperial versus Metric is a well rehearsed one and has been around for a good many years. But the issue still lives on - at least in the everyday world.
We still talk in terms of pints, feet, yards and miles and fractions. Our folk sayings would loose some of their force if we converted to metric: " A miss is as good as a kilometre" just doesn't have the same resonance as, " a miss is a good as a mile". "I'm six foot two and weigh 200 pounds" rings more of Clint Eastwood than does "I'm 1.88 metres and weigh 91 kilos". Emotions can run pretty high and even have a political or nationalistic undertone.
Driving home recently, I came across a traffic notice warning of a heavy goods vehicles entrance coming up on the main road. Originally, it said 300 metres, then 200 and 100- but clearly someone had rather forcefully objected and a makeshift alterations saying "YARDS" had been pasted on top of the offending signs. You mess with these things at your peril! But for many people, working in metric is easier and simpler to figure out. Scaling up or down is simply a matter of moving the decimal point. You are less likely to make mistakes than working in imperial mode with feet and inches. Some even argue that imperial is better. For example, how many prime numbers are there in ten compared to twelve or sixteen? But despite the introduction of metric measurement in manufacturing industry, the imperial system isn't dead.
It may be that people are used to working in the old system and find it difficult to make the transition. Or that manufacturing still works to old drawings showing imperial units - or it could be that the company is supplying to the USA market where imperial system still has a huge place. Problems can arise when one company works in metric and the other in imperial. Confusion about what are the actual measurement used can lead to some pretty basic mistakes - "I thought we were talking inches!".
Conversions can be a problem area, particularly when rounding up or down using manual calculation methods. However, for those metric triumphalists who expect to see the inch system fade away, they may surprised to learn that having a dual system, using both metric and imperial, is the superior approach. Because, in the words of Dr Nobua Suga of the Mitutoyo Institute of Metrology and author of Mitutoyo Metrology Handbook, when you cannot express a measurement in one system, you have an alternative way of describing that measurement. You therefore have more understanding of the feature being measured. In his opinion, the inch system is an elegant system which is very useful and will survive into the future.