I'm not trying to be the devil's advocate, far from it, really. Can't think of a reason to go back, however their massive attrition could be mitigated with very little to no financial impact, if that's what prevents it (highly doubt it - it's more like the spiteful minions in BUD). Examples: reinstate full and unlimited positive space travel for commuters, how about throwing it in for their immediate family members too and the list of cheap to no cost conveniences could go on and on. Making life bearable on the line, easing commuting, granting vacation in a reasonable due time goes a long way and might make some change their minds on leaving.