I don't think everyone should speak English because an important part of different cultures is the language. Without different languages, there might not be as many cultural differences across the globe, and our cultural differences keep us unique. It would definitely be easier to speak to someone from another country if you spoke the same language, but it challenges us when we learn another language. The Lord says in the Bible, "And the LORD said. 'Behold, they are one people, and they have all one language, and this is only the beginning of what they will do. And nothing that they propose to do will now be impossible for them. Come, let us go down and there confuse their language, so that they may not understand one another's speech.' so the LORD dispersed them from there over the face of the earth, and they left off building the city." (Genesis 11:6-8) So, while it would make life easier if everyone spoke the same language, it is important to be able to speak another language too as a part of improving our intelligence.
