Reworking old systems usually actually takes a lot more work than is obvious. Note that they have said that just adding a new Job takes a year. Now obviously a rework isn't going to take that long but while your not starting from scratch you do have to deal with the fact that your going to be screwing around established systems that my not have been designed to be screwed around with. Things like that can add a lot of time to the process.

I think they would love to come back and streamline their current structure if they had the time but any time they spend on that effects development of new stuff. Reworking just the SCH/SMN thing could push back the next Job to become available a year. Generally new jobs are going to interest players more than modified old ones.