Did you just get to the USA? I don't think it would take too long to realize that we aren't the UK and although the language is the "same" and you can communicate in either place with it, there are many word usages that differ. Here's a list to get you started. Perhaps that will help you realize that a nation of over 300 million people can change their own language as they see fit.
I think enough other people have already pointed out the origin of the word "soccer" and why our "rugby" has the name football.
Finally, go fuck yourself with the metric shit. That's obviously not going to happen. Would you like it if people went to your home country and said that it's time you all start speaking English? All your existing signs, recorded media, etc. all has to be re-done. Because that's about what you're asking us to do with our measurement units.