MapleStory Europe getting Kaiser soon?

What I'm trying to say is, why is this a bad thing exactly?

That is different in that 4th job was previous content and Pirates was newer content. In this case, They will get Helisium without previous content, or they will get Kaiser with a different storyline, which will require more coding and more attention from Korea.

This is bad because you don't know how the new content will mesh with the old content, given that other content is missing. It doesn't seem like there should be a problem, but you never know. It becomes unstable.