Esperanto was designed to be a universal second language. Zamenhof dreamt of a world where peoples would use their native languages between themselves but use Esperanto with those who don't understand their first language. Since Esperanto is neutral, it would have avoided the situation we have today where native English speakers are unfairly advantaged over the rest of the world. It's also worth keeping in mind that when Esperanto was designed, it was still common practice for so-called nation states to attempt to forcibly assimilate minorities under their rule, which often took form of linguistic discrimination. Adoption of Esperanto would have prevented a lot of suffering and damage.
Esperanto is pretty flexible and sometimes you can tell the native language of users from the way they use it. It can be pretty amusing. I don't think it poses the same dangers that the current dominant languages do. You can already find reports about new books being written in crippled styles that make translation into English easier, with the global market in mind. With Esperanto this would be a much smaller issue.
I think fear of Esperanto is completely misplaced. If anything, it could alleviate pressure on minority languages.