Why is it not written in French? Or Italian? Or Romansh? Because Switzerland has four official languages and English makes it easier for everyone

Not really. It's because the target audience is more academic/scientific rather than the Swiss population at large. In the latter case, it would be in the local languages. The law is relatively clear for this. English is not accepted in Switzerland as a replacement language for the "local" ones, although many people can speak or at least understand some English.