>What's the problem with keeping the accent? Why do you think an accent hinders you?

In my experience, it does, in most social contexts, and also in job interviews, as some interviewers don't feel it would be as easy for me to integrate to the rest of the team, which is true to some extent. These may all be exceptions but it's a big indicator in my opinion.

>And which language and universal accent should the world switch to?

I think any language known to me would do. When the time comes and people feel ready to accept the idea of one language (looking at the replies I got, it's not gonna happen), we'll discuss it.