SE probably won't be bringing new servers online any time soon since the existing servers are far under capacity, but it seems like there are a fair number of people wanting language-specific servers on both sides of the Japanese-English fence.

I think they should not segregate any of their existing servers, but if they bring new servers online in the future it might be a nice option to give people who really want it.

I personally want to play in an international environment so I would not want to join a one-language server.