First of all, Balmung is still the most populated server in the entirety of FFXIV.. so I don't know what your problem is.

Secondly, this issue is a direct effect of the players not SE. This does not include the people who were forcefully put in. No, this is the fault of every person who knowingly created characters and joined Balmung when it was already locked. Knowingly transferred into the server BECAUSE it was locked. That is why the server is an overpopulated mess. Everyone jam-packed themselves into one server then complain they can't/won't leave. Now it's locked even from transfer. Deal with it