A language needs to get a foothold somewhere. Ruby started on the low end and worked its way into a position of power. Java started in the enterprise and became normal thanks to catering to their needs so well. Erlang is in an awkward place where it solves certain problems well, but there is not a big class of user for it to get a foothold in. It's not better than Ruby at bring Ruby and it isn't better than Java at being Java and it isn't better than C at being C.