English is the most spoken language of most of the world, it's only natural that all websites should at least have a English option. (Outside China, where it's Mandarin.)
Open source relies on people wanting to contribute, the law of probability dictates that there's a chance (however extremely unlikely that is) that nobody will translate it, because nobody is obligated to do it.
Google translate has been known to not alwasy translate perfectly and terms and conditions are something that should have the correct translation as you are agreeing to it and is similar to a contract.
zourious
