Adopting another language as our lingua franca when English is already filling that role would be a regression. It's not saying other languages are inferior per se, they might be superior. But using any other would be an inferior choice now. It doesn't mean we can't add local flavors to it.
I am a French native speaker and I also think we should just use English and move on as a species. Interpersonnal communication is hard enough that we don't need artificial complications. Let's tackle more interesting problems. Same reason we should use a single measurement units system, mains current standard, a single currency, etc.
