It does seem like a bit too long of a wait, but I'm glad they finally announced the timeframe for the update.
I disagree that the expansion might have been a waste to get when it came out. The missions may have been a lot lighter than expected, and that's not totally made up by the new jobs. However, Campaign is a huge change to gameplay. It's now trivial to go do something useful if you're on for just a half hour, have an event coming up, or otherwise just have some free time. No more waiting to gather a full party and then feeling that you have to spend 2 hours exping; you can quickly jump to the past and start getting some ok exp. You can leave whenever you need without having to worry about replacements or giving short notice.
The rest may have been a bit wanting, but Campaign was a great addition that lets you spend however much time you want, when you want it. Now they just need to add lots of good missions and some new NMs/items in the update to really make the expansion shine. Oh yeah, and finally make those job changes they've been going on about for ages. :tounge-1: